arXiv subjects

Rabindra Basnet

Publications and source records attributed to Rabindra Basnet.

At least 19 recordsLinked to original sources

arXiv2026

Origin of High-Temperature Antiferromagnetic Order in a van der Waals Material

While Van der Waals (vdW) itinerant antiferromagnets with high Neel temperatures (TN) are highly desirable for spintronics, they remain relatively scarce. Here, we unravel the physical origin of the unusually high TN (= 250 K) in the newly identified vdW compound (Fe0.65Co0.35)4GeTe2. The substitution of Co in Fe4GeTe2 induces layer-selective Fe-Co ordering and stabilizes a robust antiferromagnetic (AFM) state primarily driven by Co moments. The AFM order is further strengthened by enhanced electronic correlations of quasi-localized Co 3d-states at the Fermi level, giving rise to an itinerant-localized duality of the 3d electrons. This interplay generates strong magnetic correlations well above TN and stabilizes low-temperature spin canting with a possible nontrivial Berry curvature. Our results establish (Fe0.65Co0.35)4GeTe2 as a rare material bridging fundamental magnetic interactions with potential applications in AFM spintronics.

cond-mat.mtrl-sci↗

arXiv2026

Light Polarization Sensitive Transistor Action in the van der Waals ferroelectric 4H-SnS2

Van der Waals (vdW) ferroelectric semiconductors provide a unique platform for exploring the interplay between spontaneous polarization, electronic transport, ion migration, and photocarrier generation at the nanoscale. Here, we establish a room-temperature ferroelectric state in SnS2 and its sensitivity to structural polytype by directly contrasting the centrosymmetric 2H-phase with the polar 4H-phase. Raman spectroscopy distinguishes the 2H and 4H polymorphs of SnS2 through their characteristic phonon fingerprints. Piezoresponse force microscopy confirms room-temperature ferroelectricity in the 4H phase, while the 2H phase exhibits no ferroelectric response. The built-in polarization in a three-terminal transistor device of the 4H-SnS2 is modulated significantly by electrostatic gating and on exposure to linear and circularly polarized light. This device reveals polarization-controlled output characteristics with distinct gate-voltage induced hysteretic response and thermally activated carrier transport, confirming p-type semiconducting behavior strongly coupled to ferroelectric polarization. The photoresponse likewise exhibits polarization-assisted carrier separation, sublinear power-law scaling, a nonmonotonic temperature response correlated with the characteristic Raman modes, ferroelectric hysteresis, and a pronounced dependence on the circular and linear polarization states of the incident laser beam. These results establish 4H-SnS2 as a promising material system for polarization-driven electronic and optoelectronic technologies, including nonvolatile memory and photoferroelectric functionalities.

cond-mat.mtrl-sci↗

arXiv2026

Chalcogen Doping Effect on the Insulator-to-Metal Transition in GdPS

Topological semimetals offer a rich platform for exploring massless fermion physics and realizing exotic properties with potential technological applications. GdPS, a magnetic semiconductor derived from the nodal-line semimetal ZrSiS family, exhibits a field-induced insulator-to-metal transition driven by exchange splitting. This transition is accompanied by an unusual, isotropic, and gigantic negative magnetoresistance, attributed to negligible magnetic anisotropy resulting from the weak spin-orbit coupling of half-filled Gd3+ 4f orbitals and light S atoms. In this work, we investigate Se substitution, which is expected to enhance spin-orbit coupling. Indeed, we observe slightly increased magnetic anisotropy in magnetotransport. Moreover, Se substitution suppresses the field-induced insulator-to-metal transition, likely due to an enlarged band gap that demands a higher exchange splitting to close. These findings provide deeper insights into the interplay between spin-orbit coupling, magnetic anisotropy, and transport behavior in GdPS, offering guidance for future materials design for desired functionalities.

cond-mat.mtrl-sci↗

arXiv2026

Photoferroelectric Coupling and Polarization-Controlled Interfacial Band Modulation in van der Waal Compound CuInP2S6

Understanding how optical excitation couples with polarization and interfacial electrostatics in van der Waals (vdW) ferroelectrics (FEs) is essential for the development of light-programmable nanoelectronic and optoelectronic devices. Here, we present direct nanoscale evidence of photoferroionic coupling in the vdW FE semiconductor CuInP2S6 (CIPS), where optical excitation jointly modulates electronic band bending, FE switching, and Cu+ ionic relaxation. The use of correlated Kelvin probe force microscopy, piezoresponse force microscopy, and conductive atomic force microscopy under above-bandgap illumination reveals illumination-induced enhancement of surface work function, persistent surface photovoltage, reduced coercive field, and positive imprint shifts. These effects arise from synergistic photocarrier redistribution and slow Cu+ migration that reshape interfacial depletion widths and internal electric fields. Illumination-assisted barrier lowering further enhances carrier injection and produces sweep-rate-dependent ferroionic transport hysteresis. Our results establish photoferroionic coupling as the governing mechanism for light-controlled band modulation and polarization stability in CIPS, providing a nanoscale framework for designing light-addressable FE memories, optoelectronic switches, and neuromorphic devices based on layered ferroionic materials.

cond-mat.mtrl-sci↗

arXiv2026

Cr3+ spin dynamics under the octahedral crystal field in van der Waals antiferromagnets

The magnetic moment in van der Waals (vdW) materials containing 3d transition metals originates from unpaired d-electron spins and their interaction with surrounding ligands. The interplay between exchange interactions and magnetic anisotropy stabilizes long-range ordering of such moments. The compound CuCrP2S6 (CCPS) presents an interesting class of vdW solids where the coupling of Cr3+ moments and ordering of Cu1+ ions give rise to a multiferroic ground state. Here we investigate the spin dynamics of Cr3+ ions in CCPS through magnetization and broadband as well as single sub-THz magnetic resonance measurements. The orbital moment of Cr3+ is quenched under the octahedral crystal field of surrounding chalcogen ions, resulting in negligible magnetic anisotropy-a feature common to Cr-based vdW antiferromagnets (AFM). Resonance spectra over a wide frequency-field-temperature range reveal quasi-2D AFM dynamics governed mainly by isotropic Cr-Cr exchange interactions, which determine the magnetic order, spin reorientation, and damping. Sub-THz resonance spectra also uncover a field-induced ferromagnetic polarization, highlighting the universal role of Cr-Cr exchange in layered Cr compounds. Moreover, persistent magnetic correlations far above the N\'eel temperature (TN ~ 32 K) points to short-range magnetic order in CCPS and motivates future studies of a possible interplay between AFM and antiferroelectric orders. These results establish CCPS as an exemplary system for exploring 2D magnetism and electric-field-tunable spintronic functionalities in layered multiferroics.

cond-mat.mtrl-sci↗

arXiv2025

Quenching the Non-Collinear Spin Order in High-Tc Layered Ferromagnet Fe5GeTe2

The realization of long-range spin order in two-dimensions (2D) has catapulted the search for layered materials with magnetic ordering above room temperature. These efforts aim to understand and enhance the spin spin interactions in 2D. An emergent class of such magnets is the layered FeNGeTe2 (N = 3, 4, and 5). Here, we investigate the magnetic states over a wide field temperature phase space in the high-Tc ferromagnet Fe5GeTe2 using magnetization, ferromagnetic resonance (FMR), and magneto-transport measurements. Our findings reveal a magnetic phase transition from a collinear to a complex non-collinear magnetic order near the temperature T* = 160 K, below which magnetic susceptibility is reduced, FMR linewidth broadened, and anomalous Hall resistivity suppressed. Such non-collinearity results from the competition between magnetocrystalline anisotropy and Dzyaloshinskii Moriya interaction arising from the unusual Fe1 ordering in two possible split sites. Our study focuses on the strategy to quench the non-collinear spin order. Substituting 40% Ni in Fe5GeTe2 is found to be one such quenching strategy. This provides deeper insights into the magnetism of a high-Tc layered-ferromagnet, offering opportunities to develop 2D magnet-based devices.

cond-mat.mtrl-sci↗

arXiv2025

Evolution of Magnetoresistance in the magnetic topological semimetals NdSbxTe2-x

Magnetic topological semimetals LnSbTe (Ln = lanthanide elements) provide a platform to study the interplay of structure, magnetism, topology, and electron correlations. Varying Sb and Te compositions in LnSbxTe2-x can effectively control the electronic, magnetic, and transport properties. Here, we report the evolution of transport properties with Sb and Te contents in NdSbxTe2-x, (0 < x < 1). Our work reveals nonmonotonic evolution in magnetoresistance with varying composition stoichiometry. Specifically, reducing Sb content x leads to strong negative magnetoresistance up to 99.9%. Such a strong magnetoresistance, which is likely attributed to the interplay between structure, magnetism, and electronic bands, establishes this material as a promising platform for investigating topological semimetal for future device applications.

cond-mat.mtrl-sci↗

arXiv2025

Large Negative Magnetoresistance in off-Stochiometric Topological Material PrSbTe

Magnetic topological materials LnSbTe (Ln = lanthanide) have attracted intensive attention because of the presence of interplay between magnetism, topological, and electron correlations depending on the choices of magnetic Ln elements. Varying Sb and Te composition is an efficient approach to control structural, magnetic, and electronic properties. Here we report the composition-dependent properties in PrSbxTe2-x. We identified the tetragonal-to-orthorhombic structure transitions in this material system, and very large negative magnetoresistance in the x = 0.3 composition, which might be ascribed to the coupling between magnetism and transport. Such unusual magnetotransport enables PrSbxTe2-x topological materials as a promising platform for device applications.

cond-mat.mtrl-sci↗

arXiv2025

Large Negative Magnetoresistance in Antiferromagnetic Gd2Se3

Rare earth chalcogenides provide a great platform to study exotic quantum phenomena such as superconductivity and charge density waves. Among various interesting properties, the coupling between magnetism and electronic transport has attracted significant attention. Here, we report the investigation of such coupling in {alpha}-Gd2Se3 single crystals through magnetic, calorimetric, and transport property measurements. {alpha}-Gd2Se3 is found to display an antiferromagnetic ground state below 11 K with metamagnetic spin-flop transitions. The magnetic fluctuations remain strong above the transition temperature. Transport measurements reveal an overall metallic transport behavior with a large negative magnetoresistance of ~ 65% near the magnetic transition temperature, together with positive MR near the field-induced spin-flop transitions, which can be understood in terms of the suppression of spin scattering by the magnetic field.

cond-mat.mtrl-sci↗

arXiv2024

Medium-entropy Engineering of magnetism in layered antiferromagnet CuxNi2(1-x)CrxP2S6

Engineering magnetism in layered magnets could result in novel phenomena related to two-dimensional (2D) magnetism, which can be useful for fundamental research and practical applications. Extensive doping efforts such as substitution and intercalation have been adopted to tune antiferromagnetic (AFM) properties in M2P2X6 compounds. The substitutional doping in this material family has mainly focused on bimetallic substitution. Recently, the metal substitution can also be extended to more than two metal elements, leading to medium and high-entropy alloys (MEAs and HEAs), which are fairly underexplored in layered magnetic systems including M2P2X6. In this work, we explored the magnetic properties of the previously unreported Cu- and Cr-substituted Ni2P2S6 i.e., CuxNi2(1-x)CrxP2S6. Our study reveals a relatively systematic evolution of AFM phases with substitution than that observed in traditional bimetallic substitution in M2P2X6. Furthermore, the Cu and Cr substitutions in Ni2P2S6 are found to enhance the ferromagnetic (FM) correlation, which is also accompanied by a possible weak FM phase at low temperatures for the intermediate compositions from 0.32 to 0.80. Our work provides a strategy to establish ferromagnetism in AFM M2P2X6 that can also be used for property tuning in other layered magnets.

cond-mat.mtrl-sci↗

arXiv2024

Understanding and Tuning Magnetism in van der Waals-type Metal Thiophosphates

Over the past two decades, significant progress in two-dimensional (2D) materials has invigorated research in condensed matter and material physics in low dimensions. While traditionally studied in three-dimensional systems, magnetism has now been extended to the 2D realm. Recent breakthroughs in 2D magnetism have captured substantial interest from the scientific community, owing to the stable magnetic order achievable in atomically thin layers of the van der Waals (vdW)-type layered magnetic materials. These advances offer an exciting platform for investigating related phenomena in low dimensions and hold promise for spintronic applications. Consequently, vdW magnetic materials with tunable magnetism have attracted significant attention. Specifically, antiferromagnetic metal thiophosphates MPX3 (M = transition metal, P = phosphorus, X = chalcogen) have been investigated extensively. These materials exhibit long-range magnetic orders spanning from bulk to the 2D limit. The magnetism in MPX3 arises from localized moments associated with transition metal ions, making it tunable via substitutions and intercalations. In this review, we focus on such tuning by providing a comprehensive summary of various metal- and chalcogen-substitution and intercalation studies, along with the mechanism of magnetism modulation, and a perspective on the development of this emergent material family.

cond-mat.mtrl-sci↗

arXiv2024

Tuning Magnetism in Ising-type van der Waals Magnet FePS3 by Lithium Intercalation

Recently, layered materials transition metal thiophosphate MPX3 (M = transition metals, X = S or Se) have gained significant attention because of their rich magnetic, optical, and electronic properties. Specifically, the diverse magnetic structures and the robustness of magnetism in the two-dimensional limit have made them prominent candidates to study two-dimensional magnetism. Numerous efforts such as substitutions and interlayer intercalations have been made to tune the properties of these materials, which has greatly deepened the understanding of the underlying mechanisms that govern the properties. In this work, we focus on modifying the magnetism of Ising-type antiferromagnet FePS3 using electrochemical lithium intercalation. Our work unveils the effectiveness of electrochemical intercalation as a controllable tool to modulating magnetism, including tuning magnetic ordering temperature and inducing low temperature spin-glass state, offering an approach for implementing this material into applications.

cond-mat.mtrl-sci↗

arXiv2024

Insulator-to-Metal Transition and Isotropic Gigantic Magnetoresistance in Layered Magnetic Semiconductors

Magnetotransport, the response of electrical conduction to external magnetic field, acts as an important tool to reveal fundamental concepts behind exotic phenomena and plays a key role in enabling spintronic applications. Magnetotransport is generally sensitive to magnetic field orientations. In contrast, efficient and isotropic modulation of electronic transport, which is useful in technology applications such as omnidirectional sensing, is rarely seen, especially for pristine crystals. Here we propose a strategy to realize extremely strong modulation of electron conduction by magnetic field which is independent of field direction. GdPS, a layered antiferromagnetic semiconductor with resistivity anisotropies, supports a field-driven insulator-to-metal transition with a paradoxically isotropic gigantic negative magnetoresistance insensitive to magnetic field orientations. This isotropic magnetoresistance originates from the combined effects of a near-zero spin-orbit coupling of Gd3+-based half-filling f-electron system and the strong on-site f-d exchange coupling in Gd atoms. Our results not only provide a novel material system with extraordinary magnetotransport that offers a missing block for antiferromagnet-based ultrafast and efficient spintronic devices, but also demonstrate the key ingredients for designing magnetic materials with desired transport properties for advanced functionalities.

cond-mat.mtrl-sci↗

arXiv2024

Evolution of Magnetism in Magnetic Topological Semimetal NdSb$_x$Te$_{2-x+\delta}$

Magnetic topological semimetals LnSbTe (Ln = Lanthanide) have attracted intensive attention because of the presence of interplay between magnetism, topological, and electron correlations depending on the choices of magnetic Ln elements. Recently, varying Sb-Te composition has been found to effectively control the electronic and magnetic states in LnSbxTe$_{2-x}$. With this motivation, we report the evolution of magnetic properties with Sb-Te substitution in NdSb$_x$Te$_{2-x+\delta}$. Our work reveals the interesting non-monotonic change in magnetic ordering temperature with varying composition stoichiometry. In addition, reducing the Sb content x drives the reorientation of moments from in-plane (ab-plane) to out-of-plane (c-axis) direction that results in the distinct magnetic structures for two end compounds NdTe$_2$ ($x = 0$) and NdSbTe ($x = 1$). Furthermore, the moment orientation in NdSb$_x$Te$_{2-x+\delta}$ is also found to be strongly tunable upon application of weak magnetic field, leading to rich magnetic phases depending on the composition stoichiometry, temperature, and magnetic field. Such strong tuning of magnetism in this material establishes it as a promising platform for investigating tunable topological states and correlated topological physics.

cond-mat.mtrl-sci↗

arXiv2024

Field-induced spin polarization in lightly Cr-substituted layered antiferromagnet NiPS3

Tuning magnetic properties in layered magnets is an important route to realize novel phenomenon related to two-dimensional (2D) magnetism. Recently, tuning antiferromagnetic (AFM) properties through substitution and intercalation techniques have been widely studied in MPX3 compounds. Interesting phenomena, such as diverse AFM structures and even the signatures of ferrimagnetism, have been reported. However, long-range ferromagnetic (FM) ordering has remained elusive. In this work, we explored the magnetic properties of the previously unreported Cr-substituted NiPS3. We found that Cr substitution is extremely efficient in controlling spin orientation in NiPS3. Our study reveals a field-induced spin polarization in lightly (9%) Cr-substituted NiPS3, which is likely attributed to the attenuation of AFM interactions and magnetic anisotropy due to Cr doping. Our work provides a possible strategy to achieve FM phase in AFM MPX3, which could be useful for investigating 2D magnetism as well as potential device applications.

cond-mat.mtrl-sci↗

arXiv2024

Distinct Composition-Dependent Topological Hall Effect in Mn2-xZnxSb

Spintronics, an evolving interdisciplinary field at the intersection of magnetism and electronics, explores innovative applications of electron charge and spin properties for advanced electronic devices. The topological Hall effect, a key component in spintronics, has gained significance due to emerging theories surrounding noncoplanar chiral spin textures. This study focuses on Mn2-xZnxSb, a material crystalizing in centrosymmetric space group with rich magnetic phases tunable by Zn contents. Through comprehensive magnetic and transport characterizations, we found that the high-Zn (x>0.6) samples display THE which is enhanced with decreasing temperature, while THE in the low-Zn (x<0.6) samples show an opposite trend. The coexistence of those distinct temperature dependences for THE suggests very different magnetic interactions/structure for different compositions and underscores the strong coupling between magnetism and transport in Mn2-xZnxSb. Our findings contribute to understanding topological magnetism in centrosymmetric tetragonal lattices, establishing Mn2-xZnxSb as a unique platform for exploring tunable transport effects and opening avenues for further exploration in the realm of spintronics.

cond-mat.mtrl-sci↗

arXiv2024

Understanding and tuning magnetism in layered Ising-type antiferromagnet FePSe3 for potential 2D magnet

Recent development in two-dimensional (2D) magnetic materials have motivated the search for new van der Waals magnetic materials, especially Ising-type magnets with strong magnetic anisotropy. Fe-based MPX3 (M = transition metal, X = chalcogen) compounds such as FePS3 and FePSe3 both exhibit an Ising-type magnetic order, but FePSe3 receives much less attention compared to FePS3. This work focuses on establishing the strategy to engineer magnetic anisotropy and exchange interactions in this less-explored compound. Through chalcogen and metal substitutions, the magnetic anisotropy is found to be immune against S substitution for Se whereas tunable only with heavy Mn substitution for Fe. In particular, Mn substitution leads to a continuous rotation of magnetic moments from the out-of-plane direction towards in-plane. Furthermore, the magnetic ordering temperature displays non-monotonic doping dependence for both chalcogen and metal substitutions but due to different mechanisms. These findings provide deeper insight into the Ising-type magnetism in this important van der Waals material, shedding light on the study of other Ising-type magnetic systems as well as discovering novel 2D magnets for potential applications in spintronics.

cond-mat.mtrl-sci↗

arXiv2023

Coupling Between Magnetic and Transport Properties in Magnetic Layered Material Mn2-xZnxSb

We synthesized single crystals for Mn2-xZnxSb and studied their magnetic and electronic transport properties. This material system displays rich magnetic phase tunable with temperature and Zn composition. In addition, two groups of distinct magnetic and electronic properties, separated by a critical Zn composition of x = 0.6, are discovered. The Zn-less samples are metallic and characterized by a resistivity jump at the magnetic ordering temperature, while the Zn-rich samples lose metallicity and show a metal-to-insulator transition-like feature tunable by magnetic field. Our findings establish Mn2-xZnxSb as a promising material platform that offers opportunities to study how the coupling of spin, charge, and lattice degrees of freedom governs interesting transport properties in 2D magnets, which is currently a topic of broad interest.

cond-mat.mtrl-sci↗