arXiv subjects

C. S. Yadav

Publications and source records attributed to C. S. Yadav.

At least 19 recordsLinked to original sources

arXiv2026

Magnetoresistance in Magnetic Weyl semimetal Mn$_{3}$ZnC

The magnetoresistance (MR) in magnetic materials reveal an intriguing spin-dependent electron scattering, highlighting the role of spin polarization on the electronic transport properties. This becomes even more interesting for the topological magnetic materials where a finite Berry curvature leads to an intrinsic scattering channel also. In this report, we investigate MR of Mn$_{3}$ZnC, an antiperovskite magnetic nodal line semimetal. Mn$_{3}$ZnC shows a ferromagnetic (FM) transition at $\sim$ 420 K, followed by an ferrimagnetic (FIM) transition at $\sim$ 195 K. We focus on the interpretation of MR data and highlight the relation between MR and its magnetization. The signature of magnetization induced MR shows correlation at low magnetic fields and displays distinct behaviors in the FIM and FM states. Similar to the isothermal magnetization M(H) curve of FM and FIM state, the MR curves exhibit a sharp increase, followed by a linear behavior at higher fields. As the magnetic field varies, the cusp-like anomaly becomes more pronounced, and vanishes at the magnetic phase transition, which then reappears as the temperature increases. The sign change in the MR curves in the FIM state is attributed to a drastic change in the carrier mobility. Interestingly, this system shows a positive MR in FM state at very low field, which is quite unusual.

cond-mat.str-el↗

arXiv2026

Anomalous Transverse Response in Nodal line Semimetal Mn$_{3}$SnC

The interplay of topological surface states and magnetism gives rise to unconventional transport behaviors such as the anomalous Hall effect (AHE) and anomalous Nernst effect (ANE). Antiperovskites such as Mn$3$SnC, which are nodal-line semimetals and exhibit concurrent antiferromagnetic (AFM) and ferromagnetic (FM) ordering, provide a fertile ground for anomalous transport phenomena. Here, we report that the anomalous transport (AHE and ANE) in this compound is predominantly governed by the intrinsic Berry-curvature effect. We establish a unified relationship between the AHE and ANE using Mott's relation. Electron scattering by both AFM and FM magnons is manifested in the anomalous Nernst signal. The ratio of the anomalous Nernst conductivity to the anomalous Hall conductivity, $|α^A{xy}|/σ^A_{xy}$, constitutes a sizable fraction of $k_B/e$, indicating a strong Berry-curvature contribution to the ANE.

cond-mat.str-el↗

arXiv2026

Low temperature Spin freezing and Diffuse Magnetic Correlations in Tb$_{2}$Zr$_{2-x}$Ti$_{x}$O$_{7}$ (x = 0, 0.5)

Structural disorder in the magnetically frustrated pyrochlore system leads to intriguing magnetic states. We present the thermodynamic behavior and short range magnetic correlations in Tb$_{2}$Zr$_{2}$O$_{7}$ and Tb$_{2}$Zr$_{1.5}$Ti$_{0.5}$O$_{7}$ compounds. The parent compound Tb$_{2}$Zr$_{2}$O$_{7}$ has defect fluorite structure, which evolves toward the pyrochlore phase on Ti doping at Zr site. There is no long range magnetic order down to 0.4 K, and a magnetic field dependent spin freezing evolves below 1.25 K and 1.05 K for the parent and doped compounds, respectively. The ac susceptibility measurements indicate slow spin relaxation process below 20 K in these compounds. Inelastic neutron scattering reveals broad diffuse scattering, indicative of short range correlations at low temperature, owing to local structural distortions and persistent spin fluctuations. These results suggest a correlated, disorder influenced magnetic state in Tb$_{2}$Zr$_{2}$O$_{7}$, Tb$_{2}$Zr$_{1.5}$Ti$_{0.5}$O$_{7}$ compounds.

cond-mat.str-el↗

arXiv2026

Anomalous Hall transport in Mn$_{3}$Sn$_{0.5}$X$_{0.5}$C (X = Ge and Zn)

Mn-based antiperovskites that exhibit topological surface states show potential applications in spintronics, magnetoelectronics, and quantum devices owing to the interplay between magnetism and topology. In this family of compounds, Mn$3$SnC exhibits a concurrent ferromagnetic and antiferromagnetic ground state below $T \sim 285$ K, along with a Berry curvature driven anomalous Hall effect. Here, we report the anomalous Hall effect in Ge- and Zn-doped Mn$3$SnC compounds, namely Mn$3$Sn${0.5}$Ge${0.5}$C (MSGC) and Mn$3$Sn${0.5}$Zn${0.5}$C (MSZC). MSGC undergoes a paramagnetic to concurrent antiferromagnetic and ferromagnetic transition at $T_C \sim 300$ K, whereas MSZC exhibits a paramagnetic to ferromagnetic transition at $T_C \sim 240$ K, followed by a ferromagnetic to ferrimagnetic transition at $T_N \sim 170$ K. The electronic transport in these compounds is governed by electron-phonon and electron-magnon scattering and shows anomalous Hall resistivity $ρ^A_{xy}$. Our analysis indicates that the anomalous Hall effect arises from contributions of skew scattering and intrinsic Berry curvature mechanisms, with electron-phonon and electron-magnon scattering playing an important role in skew scattering at high temperatures. Ge and Zn doping in Mn$_3$SnC significantly enhances the anomalous Hall conductivity.

cond-mat.mtrl-sci↗

arXiv2025

Tuning Magnetic and Electronic Properties of Double Perovskite La$_2$CoIr$_{1-x}$Ti$_x$O$_6$

The La$_2$CoIr$_{1-x}$Ti$_x$O$_6$ double perovskite series serves as an effective platform for investigating the evolution of magnetic and electronic properties as a function of chemical pressure (doping) or hydrostatic pressure due to the interplay between the electrons correlation and spin-orbit coupling. In this study, the substitution of nonmagnetic Ti$^{4+}$ at the magnetic Ir$^{4+}$-site leads to a systematic decrease in unit cell volume keeping the monoclinic symmetry throughout, reflecting the effect of chemical pressure along with a gradual suppression of magnetic interactions. The parent compound ($x =$ 0) exhibits a ferromagnetic-like state with a Curie temperature of 92 K, which continuously evolves into an antiferromagnetic ground state upon full Ti substitution ($x =$ 1) with a Neel temperature of 14.6 K. Isothermal magnetization measurements reveal a hysteresis behavior with step-like feature at zero field, indicative of a noncollinear magnetic ordering. Additionally, the enhancement of magnetization under hydrostatic pressure on La$_2$CoIrO$_6$ suggests the presence of piezomagnetic behavior. Thermal expansion measurements on La$_2$CoIrO$_6$ highlight a coupling between spin and lattice degrees of freedom. The pressure dependence of the transition temperature in the zero-pressure limit, calculated using Ehrenfest's relation, shows good agreement with magnetization data under applied pressure. First-principles density functional theory (DFT) calculations preformed for $x =$ 0, 0.5 and 1, further reveal that strong SOC associated with Ir plays a decisive role in shaping the electronic band structure, with the insulating gap progressively widening as Ti content increases from 0.28 eV ($x =$ 0), 0.44 eV ($x =$ 0.5), and 1.01 eV ($x =$ 1). The magnetic moment decreased more than 50\% for $x =$ 0.5, showing the decrease in magnetic exchange pathways.

cond-mat.mtrl-sci↗

arXiv2025

New plasmon-like mode in PdTe$_{2}$: Raman scattering and memory function study

PdTe$_2$ is a type II Dirac semimetal that has garnered significant attention due to its intriguing electronic and topological properties. Here, we report temperature dependent Raman scattering study of PdTe$_2$ in the temperature range from 10 K to 300 K. Our study reveals emergence of a new unreported peak below 100 K, centered around 250 cm$^{-1}$. We argue that the new mode is not a phonon mode because the Raman spectra calculated using Density Functional Theory shows only two intense peaks at 85 $ cm^{-1}$ and 128 $cm^{-1}$. To ascertain the origin of this new peak, we constructed a microscopic model of electrons coupling to a single plasmon mode at 250 $cm^{-1}$ and using the memory function formalism, we obtained that the Raman relaxation rate is linear in frequency. We also performed phenomenological analysis of the Raman response from the experimental data and computed frequency dependent Raman relaxation rate, which is also found to exhibit a linear dependence on frequency. With the congruence of our theoretical and phenomenological results we could ascertain that the new mode observed at low temperatures is indeed a plasmon-like mode. Further, phonon frequencies and line widths of the two phonon modes exhibit anomalous behavior above 100 K.

cond-mat.str-el↗

arXiv2024

Signature of point nodal superconductivity in the Dirac semimetal PdTe

Recent Angle-Resolved Photo-emission Spectroscopy (ARPES) experiments [Phys. Rev. Lett. 130, 046402 (2023)] on PdTe, a 3D-Dirac semimetal and a superconductor with the transition temperature Tc ~ 4.3 K, have revealed compelling evidence of the presence of bulk nodes in the superconducting order parameter. To investigate the validity of this proposition, here we present a detailed investigation of the magnetic field dependence of the specific heat of PdTe down to temperatures ~ 58 mK. We observed that the low temperature specific heat of PdTe with an externally applied magnetic field exhibits a power-law field dependence, a characteristic of unconventional superconductivity. Furthermore, the zero-field low-temperature electronic specific heat follows a cubic temperature dependence, which is a signature of the presence of bulk point nodes in PdTe. These intriguing observations suggest that PdTe is a rare and fascinating topological material that exhibits both Dirac semimetallic properties and superconductivity with point nodal gap symmetry.

cond-mat.supr-con↗

arXiv2024

Slow Spin Relaxation and Low-Temperature Spin Freezing in Disordered Fluorite Ho$_2$Zr$_2$O$_7$

We report on the origin of spin freezing in the disordered fluorite Ho$_2$Zr$_2$O$_7$. The system is investigated by low-temperature heat capacity as well as by DC and AC magnetization. While the system does not show a long-range magnetic order down to at least $T = 280$~mK, we observe signatures of slow spin dynamics, magnetic field induced relaxation processes at relatively high temperatures, and a spin-frozen state below $T = 0.6$~K. Our results suggest that similar to the canonical spin ice systems Ho$_2$Ti$_2$O$_7$ [Ehlers 2004] and Dy$_2$Ti$_2$O$_7$ [Snyder 2001], spin freezing in Ho$_2$Zr$_2$O$_7$ is preceded by two slow spin relaxation processes; the first forms a field-induced region extending to at least 18~K and the second is rather field-independent and appears at $T_{\mathrm g2} = 1$~K [Ramon 2020].

cond-mat.str-el↗

arXiv2024

Magnetotransport and thermoelectric studies of antiperovskite semimetal: Mn3SnC

We explore the magnetotransport and thermoelectric (Seebeck and Nernst coefficients) properties of Mn3SnC an antiperovskite magnetic Nodal line semimetal. Mn3SnC shows paramagnetic (PM) to concurrent antiferromagnetic (AFM)/ferromagnetic (FM) transition at 286 K. The electrical resistivity and Seebeck coefficient indicate the importance of electron magnon scattering in the concurrent AFM/FM regime. We observed a large positive magnetoresistance (MR) of 8.2 at 8 T field near magnetic transition, in the otherwise negative MR behaviour for low temperatures. The electrical resistivity and MR show a weak thermal hysteresis around the boundary of transition temperature and the width of hysteresis decreases as magnetic field increases. Interestingly the Hall and Seebeck coefficients change sign from positive to negative below the transition temperature, highlighting the different scattering for holes and electrons in this multi-band system. The Seebeck and Nernst signal exhibit two sharp anomalies; one at the transition temperature and another at 50 K. The anomaly at magnetic transition in the Nernst signal disappear at 8 T magnetic field, owing to the reduction of magnetic fluctuation. A pseudo-gap near the Fermi level produces an upturn with a broad minimum in the Seebeck signal.

cond-mat.str-el↗

arXiv2024

Extended Kohler's scaling, a low temperature anomaly and Isosbestic point in the charge density wave state of 1T-VSe$_2$

1T-VSe$_2$ is a narrow band transition metal chalcogenide that shows charge density wave (CDW) state below $T_{CDW}$ = 110 K. Here, we have explored the relevance of Kohler's rule and the thermal transport properties of VSe$_2$ across the CDW state. The magnetoresistance (MR) follows Kohler's rule above $T_{CDW}$, while an extended Kohler's rule is employed below $T_{CDW}$. Interestingly, we observed an anomaly in MR at T = 20 K, below which MR value decreases on lowering temperature. This anomaly is also reflected in the slope ($κ$) of Kohler's plots and the relative change in the thermal excitation induced carrier density ($n_T$) also. The $T_{CDW}$ remains largely unaffected in both electrical resistivity ($ρ(T)$) and longitudinal Seebeck coefficient ($\it{S_{xx}}$) even under a strong magnetic field of 14 Tesla. However, the application of magnetic field enhances the peak intensity of $\it{S_{xx}}$ at T $\sim$ 60 K. Additionally, $\it{S_{xx}(T)}$ curves measured at different fields exhibit a crossover at T = 20 K, which suggest the existence of unique feature in the CDW state of VSe$_2$ \textit{i.e.} a locally exact isosbestic point.

cond-mat.str-el↗

arXiv2024

Chiral anomaly and positive longitudinal magnetoresistance in the type-II Dirac semimetals $\it{A}_x$PdTe$_2$ (\textit{A} = Cu, Ag)

The Planar Hall effect (PHE) in topological materials has been a subject of great interest in recent years. Generally, it is understood to originate from the chiral-anomaly (CA) induced charge pumping between doubly degenerate Weyl nodes. However, the occurrence of PHE in the materials with positive and anisotropic orbital magnetoresistance has raised questions about CA being the sole origin of this effect. Here, we report the PHE, magnetoresistance, and thermal transport properties (Seebeck and Nernst coefficients) on the Ag intercalated PdTe$_2$. We observe positive longitudinal magnetoresistance, the linear field dependence of the amplitude of PHE, and a prolate pattern in the parametric plots. The planar Hall resistivity and anisotropic magnetoresitance fits well with theoretical study of CA being the origin of PHE. So, our observations are consistent with Weyl physics dominating the PHE in PdTe$_2$, Cu$_{0.05}$PdTe$_2$, and Ag$_{0.05}$PdTe$_2$. We further support our data with a theoretical model that reproduces the qualitative experimental features. In addition, we have calculated the Seebeck ($\it{S}$) and Nernst ($ν$) coefficients for PdTe$_2$ and Cu and Ag intercalated compounds. The estimated values of Fermi energy for the Cu and Ag intercalated compounds are respectively two times and three times larger than that of PdTe$_2$.

cond-mat.str-el↗

arXiv2023

Muon spin relaxation and emergence of disorder-induced unconventional dynamic magnetic fluctuations in Dy$_{2}$Zr$_{2}$O$_{7}$

The disordered pyrochlore oxide Dy$_{2}$Zr$_{2}$O$_{7}$ shows the signatures of field-induced spin freezing with remnant zero-point spin-ice entropy at 5 kOe magnetic field. We have performed zero-field and longitudinal field Muon spin relaxation ($μ$SR) studies on Dy$_{2}$Zr$_{2}$O$_{7}$. Our zero field studies reveal the absence of both long-range ordering and spin freezing down to 62 mK. The $μ$SR relaxation rate exhibits a temperature-independent plateau below 4 K, indicating a dynamic ground state of fluctuating spins similar to the well-known spin ice system Dy$_{2}$Ti$_{2}$O$_{7}$. The low-temperature spin fluctuations persist in the longitudinal field of 20 kOe as well and show unusual field dependence of the relaxation rate, which is uncommon for a spin-liquid system. Our results, combined with the previous studies do not show any evidence of spin ice or spin glass ground state, rather point to a disorder-induced dynamic magnetic ground state in the Dy$_{2}$Zr$_{2}$O$_{7}$ material.

cond-mat.str-el↗

arXiv2023

Electronic Transport Studies of Ag-doped Bi2Se3 Topological Insulator

The structural, magnetotransport, and angle-resolved photoemission spectroscopy (ARPES) of Ag-doped Bi2Se3 single crystals are presented. Temperature dependent resistivity exhibits metallic behavior with a slope change above 200 K for Ag-doped Bi2Se3. The magnetoresistance shows positive quadratic dependence at low fields satisfying Kohler's rule. Hall resistivity measurement shows that electrons are dominant charge carriers. Furthermore, these results agree well with the ARPES spectra observed at T = 20 K, where the Fermi level lies inside the bulk conduction band. The Dirac point of the topological surface states is shifted toward higher binding energy (~ 0.12 eV) for Ag-doped samples as compared to pristine Bi2Se3.

cond-mat.str-el↗

arXiv2023

Magneto-Transport and High-Resolution Angle-Resolved Photoelectron Spectroscopy Studies of Palladium Doped Bi$_{2}$Te$_{3}$

We have performed magneto-transport and high-resolution angle-resolved photoelectron spectroscopy (ARPES) measurements on palladium (Pd) doped topological insulator Pd$_{x}$Bi$_{2}$Te$_{3}$ (0 $\leq$ x $\leq$ 0.20) single crystals. We have observed unusually high values of magnetoresistance ($\sim$ 1500%) and mobility ($\sim$ 93000 cm$^{2}$V$^{-1}$s$^{-1}$) at low temperatures for pristine Bi2Te3 that decrease on Pd doping. The Shubnikov-de Haas (SdH) oscillations have been detected for x = 0.05, 0.10, confirming the presence of 2D topological surface states (TSSs) for these samples. The Hall measurement shows the crossover from n-type charge carriers in pristine Bi$_{2}$Te$_{3}$ to p-type charge carriers upon Pd doping. The ARPES measurements show that the conduction band crosses the Fermi level for pristine Bi$_{2}$Te$_{3}$, and the Dirac point of the TSSs and bulk-derived valence bands indicated shift to lower binding energy upon Pd doping in a rigid-band-like way up to x $\sim$0.10. Based on the comparison of the parameters obtained from the SdH and ARPES measurements, the reduction in the kF value in the magneto-transport measurements likely due to the band bending induced by the Schottky barrier.

cond-mat.str-el↗

arXiv2021

Planar Hall effect in Cu intercalated PdTe$_2$

We present the Planar Hall effect studies on the Cu intercalated type-II Dirac semimetal PdTe$_{2}$. The electrical resistivity exhibits a positive field dependence both in perpendicular and parallel field directions, causing non-zero anisotropy. The longitudinal magnetoresistance shows almost linear field dependence at low temperatures. A tilted prolate spheroid shaped orbits are observed in parametric plot between transverse and longitudinal resistivities. Our study suggest that for the type-II Dirac semimetal materials with positive longitudinal magnetoresistance, the origin of Planar Hall effect cannot be asserted with certainty to the topological or non-topological without taking into account the anisotropy of Fermi surface.

cond-mat.str-el↗

arXiv2021

Structure and magnetic studies of geometrically frustrated disordered pyrochlores A$_{2}$Zr$_{2}$O$_{7}$: (A = Eu, Gd, Er)

The spin ice system Dy$_{2}$Ti$_{2}$O$_{7}$ exhibits strong frequency-dependent spin-freezing at $\sim$ 16 K temperature. Although it has been a matter of discussion for years, the origin of this unusual spin freezing is still unknown. The replacement of Ti with isovalent Zr leads to the dynamic magnetic ground state at low temperatures in Dy$_{2}$Zr$_{2}$O$_{7}$ and prevents the formation of high-temperature spin freezing. Interestingly the high-temperature spin freezing re-emerges in the presence of the magnetic field. In this direction, we have studied a series of disordered pyrochlore oxides A$_{2}$Zr$_{2}$O$_{7}$ (A = Eu, Gd, Er) and compared their crystal structure, magnetic, and heat capacity behavior with that of Dy$_{2}$Zr$_{2}$O$_{7}$ and Ho$_{2}$Zr$_{2}$O$_{7}$ systems. Our study shows that depending on the disordered parameter, the spin-freezing behavior can be retained by slowing down the spin dynamic with a suitable choice of the magnetic field. We observe that unlike titanates, modification at the rare earth site does not make considerable change in the magnetic ground state of these zirconates compounds.

cond-mat.str-el↗

arXiv2021

Evolution of spin freezing transition and structural, magnetic phase diagram of Dy$_{2-x}$La$_x$Zr$_2$O$_7$; $x$ = 0-2.0

Dy$_{2}$Zr$_{2}$O$_{7}$ a disordered pyrochlore system, exhibits the spin ice freezing under the application of magnetic field. Our studies suggest the stabilization of pyrochlore phase in Dy$_{2-x}$La$_{x}$Zr$_{2}$O$_{7}$ with the substitution of nonmagnetic La, along with the biphasic mixture for the intermediate compositions. We observed that the higher La compositions (1.5 $\leq$ x $\leq$ 1.9), show spin freezing (T $\sim$ 17 K) similar to the field induced spin ice freezing for low La compositions (0 $\leq$ x $\leq$ 0.5), and the well known spin ice systems Dy$_{2}$Ti$_{2}$O$_{7}$ and Ho$_{2}$Ti$_{2}$O$_{7}$. The low temperature magnetic state for higher La compositions (1.5 $\leq$ x $\leq$ 1.9) culminates into spin glass state below 6 K. The Cole-Cole plot and Casimir-du Pr$\acute{e}$ fit shows narrow distribution of spin relaxation time in these compounds.

cond-mat.str-el↗

arXiv2021

Field induced spin freezing and low temperature heat capacity of disordered pyrochlore oxide Ho$_{2}$Zr$_{2}$O$_{7}$

Spin ice materials are the model systems that have a zero-point entropy as \textit{T} $\rightarrow$ 0 K, owing to the frozen disordered states. Here, we chemically alter the well-known spin ice Ho$_{2}$Ti$_{2}$O$_{7}$ by replacing Ti sites with isovalent but larger Zr ion. Unlike the Ho$_{2}$Ti$_{2}$O$_{7}$ which is a pyrochlore material, Ho$_{2}$Zr$_{2}$O$_{7}$ crystallizes in disordered pyrochlore structure. We have performed detailed structural, ac magnetic susceptibility and heat capacity studies on Ho$_{2}$Zr$_{2}$O$_{7}$ to investigate the interplay of structural disorder and frustrated interactions. The zero-field ground state exhibits large magnetic susceptibility and remains dynamic down to 30 mK without showing Pauling's residual entropy. The dynamic state is suppressed continuously with the magnetic field and freezing transition evolves ($\sim$ 10 K) at a field of $\sim$ 10 kOe. These results suggest that the alteration of chemical order and local strain in Ho$_{2}$Ti$_{2}$O$_{7}$ prevents the development of spin ice state and provides a new material to study the geometrical frustration based on the structure.

cond-mat.str-el↗