arXiv subjects

Eran Maniv

Publications and source records attributed to Eran Maniv.

13 recordsLinked to original sources

arXiv2025

$\pi$/4 phase shift in the angular magnetoresistance of infinite layer nickelates

The discovery of superconductivity in nickelates has generated significant interest in condensed matter physics. Nickelate superconductors, which are hole-doped within the layered structure of RNiO$_2$, share structural similarities with high-$T_c$ cuprate superconductors. However, despite similarities in formal valence and crystal symmetry, the fundamental nature of the superconducting state and the parent compound phase in nickelates remains elusive. Strong electronic correlations in infinite-layer nickelates suggest a potentially complex phase diagram, akin to that observed in cuprates, yet a key question about the magnetic ground state remains unanswered. Through magnetoresistance measurements across varying field strengths and orientations, we observe distinct angular-dependent magnetoresistance (AMR) oscillations with four-fold symmetry. Notably, this four-fold symmetry displays a $\pi/4$ phase shift with doping or applied magnetic field. Our findings parallel behaviors in electron-doped cuprates, suggesting that a static or quasi-static magnetic order exists in the infinite-layer nickelates, echoing characteristics of electron-doped cuprates. Furthermore, our modeling of the system reveals that the AMR is directly related to the underlying antiferromagnetic order, reinforcing this interpretation.

cond-mat.supr-con↗

arXiv2025

Field-induced spin dynamics in i-MAX Tb compound

We report a comprehensive study of spin dynamics in the (Mo2/3Tb1/3)2AlC i-MAX compound using ac susceptibility measurements across a range of magnetic fields. Unique behaviors were observed, including spin dynamics in the kHz range between mu_0 H~0.2T-6T, indicating a non-trivial superparamagnetic state, suggesting that the compound acts as a transitional system within the i-MAX family, bridging stable spin-dynamic materials and fluctuation-dominated ones. Field- and frequency-dependent magnetic phase transitions, coupled with relaxation behaviors, reveal complex interactions between spin density waves and superparamagnetic components. These findings, corroborated by uSR studies, deepen our understanding of magnetic phase diagrams and field-induced phenomena in i-MAX systems, laying the groundwork for further exploration of their unique properties and applications.

cond-mat.str-el↗

arXiv2024

Hidden magnetic phases in i-MAX compounds

We uncover a high-field magnetic phase in i-MAX compounds exhibiting a canted antiferromagnetic (AFM) order with unprecedented properties, revealed through NMR and AC susceptibility. Intriguingly, as the atomic number of Rare Earth increases, the transition field of this canted AFM phase grows at the expense of the lower-field AFM state. Our findings point to the complexity of the magnetic structure in i-MAX compounds, demonstrating a non-trivial evolution of their phase diagram while increasing both the atomic number of the Rare Earth element and the external field.

cond-mat.str-el↗

arXiv2024

Dark Metastable Conduction Channels near a Metal-Insulator Transition

Materials that transition between metal and insulator, the two main states that distinguish all solids, are fascinating because they underlie many mysteries at the frontier of solid state physics. In 1T-TaS$_{2}$, the metal-insulator transition is linked to a metastable hidden state arising within a chiral charge density wave (CDW) whose basic nature remains an open question. In this work, we show that pulses of current through these materials create current-carrying filamentary channels that distinguish the 'metallic' hidden state and 'insulating' CDW states. These channels have remained dark to previous measurements, and yet are directly linked to the properties of the hidden state. We leverage the metastability of these conduction channels to demonstrate electrical control of their creation, erasure and location. Our findings show that physical elements, such as boundaries and interfaces, play a key role in the properties of the hidden state characterizing the metal-insulator transition. We suggest new possibilities for in-situ electrical design of synaptic components with possible applications to neuromorphic computing.

cond-mat.str-el↗

arXiv2021

Long-range, Non-local Switching of Spin Textures in a Frustrated Antiferromagnet

Antiferromagnetic spintronics is an emerging area of quantum technologies that leverage the coupling between spin and orbital degrees of freedom in exotic materials. Spin-orbit interactions allow spin or angular momentum to be injected via electrical stimuli to manipulate the spin texture of a material, enabling the storage of information and energy. In general, the physical process is intrinsically local: spin is carried by an electrical current, imparted into the magnetic system, and the spin texture then rotates. The collective excitations of complex spin textures have rarely been utilized in this context, even though they can in principle transport spin over much longer distances, using much lower power. In this study, we show that spin information can be transported and stored non-locally in the material Fe$_x$NbS$_2$. We propose that collective modes leverage the strong magnetoelastic coupling in the system to achieve this, revealing a novel way to store spin information in complex magnetic systems

cond-mat.str-el↗

arXiv2021

Highly tunable magnetic phases in transition metal dichalcogenide Fe$_{1/3+\delta}$NbS$_2$

Layered transition metal dichalcogenides (TMDCs) host a plethora of interesting physical phenomena ranging from charge order to superconductivity. By introducing magnetic ions into 2H-NbS$_2$, the material forms a family of magnetic intercalated TMDCs T$_x$NbS$_2$ (T = 3d transition metal). Recently, Fe$_{1/3+\delta}$NbS$_2$ has been found to possess intriguing resistance switching and magnetic memory effects coupled to the N\'{e}el temperature of T$_N \sim 45$ K [1,2]. We present comprehensive single crystal neutron diffraction measurements on under-intercalated ($\delta \sim -0.01$), stoichiometric, and over-intercalated ($\delta \sim 0.01$) samples. Magnetic defects are usually considered to suppress magnetic correlations and, concomitantly, transition temperatures. Instead, we observe highly tunable magnetic long-ranged states as the Fe concentration is varied from under-intercalated to over-intercalated, that is from Fe vacancies to Fe interstitials. The under- and over- intercalated samples reveal distinct antiferromagnetic stripe and zig-zag orders, associated with wave vectors $k_1$ = (0.5, 0, 0) and $k_2$ = (0.25, 0.5, 0), respectively. The stoichiometric sample shows two successive magnetic phase transitions for these two wave vectors with an unusual rise-and-fall feature in the intensities connected to $k_1$. We ascribe this sensitive tunability to the competing next nearest neighbor exchange interactions and the oscillatory nature of the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism. We discuss experimental observations that relate to the observed intriguing switching resistance behaviors. Our discovery of a magnetic defect tuning of the magnetic structure in bulk crystals Fe$_{1/3+\delta}$NbS$_2$ provides a possible new avenue to implement controllable antiferromagnetic spintronic devices.

cond-mat.mtrl-sci↗

arXiv2020

Collective spin dynamics under dissipative spin Hall torque

Current-induced spin torques in layered magnetic heterostructures have many commonalities across broad classes of magnetic materials. These include not only collinear ferromagnets, ferrimagnets, and antiferromagnets, but also more complex noncollinear spin systems. We develop a general Lagrangian-Rayleigh approach for studying the role of dissipative torques, which can pump energy into long-wavelength magnetic dynamics, causing dynamic instabilities. While the Rayleigh structure of such torques is similar for different magnetic materials, their consequences depend sensitively on the nature of the order and, in particular, on whether there is a net magnetic moment. The latter endows the system with a unipolar switching capability, while magnetically compensated materials tend to evolve towards limit cycles, at large torques, with chirality dependent on the torque sign. Apart from the ferromagnetic and antiferromagnetic cases, we discuss ferrimagnets, which display an intricate competition between switching and limit cycles. As a simple case for compensated noncollinear order, we consider isotropic spin glasses, as well as a scenario of their coexistence with a collinear magnetic order.

cond-mat.mes-hall↗

arXiv2020

Antiferromagnetic Switching Driven by the Collective Dynamics of a Coexisting Spin Glass

The theory behind the electrical switching of antiferromagnets is premised on the existence of a well defined broken symmetry state that can be rotated to encode information. A spin glass is in many ways the antithesis of this state, characterized by an ergodic landscape of nearly degenerate magnetic configurations, choosing to freeze into a distribution of these in a manner that is seemingly bereft of information. In this study, we show that the coexistence of spin glass and antiferromagnetic order allows a novel mechanism to facilitate the switching of the antiferromagnet Fe$_{1/3+\delta}$NbS$_2$, which is rooted in the electrically-stimulated collective winding of the spin glass. The local texture of the spin glass opens an anisotropic channel of interaction that can be used to rotate the equilibrium orientation of the antiferromagnetic state. The use of a spin glass' collective dynamics to electrically manipulate antiferromagnetic spin textures has never been applied before, opening the field of antiferromagnetic spintronics to many more material platforms with complex magnetic textures.

cond-mat.str-el↗

arXiv2020

Half-magnetization plateau and the origin of threefold symmetry breaking in an electrically-switchable triangular antiferromagnet

We perform high-field magnetization measurements on the triangular lattice antiferromagnet Fe$_{1/3}$NbS$_2$. We observe a plateau in the magnetization centered at approximately half the saturation magnetization over a wide range of temperature and magnetic field. From density functional theory calculations, we determine a likely set of magnetic exchange constants. Incorporating these constants into a minimal Hamiltonian model of our material, we find that the plateau and of the $Z_3$ symmetry breaking ground state both arise from interplane and intraplane antiferromagnetic interactions acting in competition. These findings are pertinent to the magneto-electric properties of Fe$_{1/3}$NbS$_2$, which allow electrical switching of antiferromagnetic textures at relatively low current densities.

cond-mat.str-el↗

arXiv2019

Observation of three-state nematicity in the triangular lattice antiferromagnet Fe$_{1/3}$ NbS$_2$

Nematic order is the breaking of rotational symmetry in the presence of translational invariance. While originally defined in the context of liquid crystals, the concept of nematic order has arisen in crystalline matter with discrete rotational symmetry, most prominently in the tetragonal Fe-based superconductors where the parent state is four-fold symmetric. In this case the nematic director takes on only two directions, and the order parameter in such "Ising-nematic" systems is a simple scalar. Here, using a novel spatially-resolved optical polarimetry technique, we show that a qualitatively distinct nematic state arises in the triangular lattice antiferromagnet Fe$_{1/3}$NbS$_2$. The crucial difference is that the nematic order on the triangular lattice is a Z$_3$, or three-state Potts-nematic order parameter. As a consequence, the anisotropy axes of response functions such as the resistivity tensor can be continuously re-oriented by external perturbations. This discovery provides insight into realizing devices that exploit analogies with nematic liquid crystals.

cond-mat.str-el↗

arXiv2019

Electrical switching in a magnetically intercalated transition metal dichalcogenide

Recent advances in tuning the correlated behavior of graphene and transition-metal dichalcogenides (TMDs) have opened a new frontier in the study of many-body physics in two dimensions and promise exciting possibilities for new quantum technologies. An emerging field where these materials have yet to make a deep impact is the study of antiferromagnetic (AFM) spintronics - a relatively new research direction that promises technologies that are insensitive to external magnetic fields, fast switching times, and reduced crosstalk. In this study we present measurements on the intercalated TMD Fe1/3NbS2 which exhibits antiferromagnetic ordering below 42K. We find that current densities on the order of 10^4 A/cm^2 can reorient the magnetic order, the response of which can be detected in the sample's resistance. This demonstrates that Fe1/3NbS2 can be used as an antiferromagnetic switch with electronic "write-in" and "read-out". This switching is found to be stable over time and remarkably robust to external magnetic fields. Fe1/3NbS2 is a rare example of an AFM system that exhibits fully electronic switching behavior in single crystal form, making it appealing for low-power, low-temperature memory storage applications. Moreover, Fe1/3NbS2 is part of a much larger family of magnetically intercalated TMDs, some of which may exhibit the switching behavior at higher temperatures and form a platform from which to build tunable AFM spintronic devices.

cond-mat.str-el↗

arXiv2019

Tunable Giant Exchange Bias in an Intercalated Transition Metal Dichalcogenide

The interplay of symmetry and quenched disorder leads to some of the most fundamentally interesting and technologically important properties of correlated materials. It also poses the most vexing of theoretical challenges. Nowhere is this more apparent than in the study of spin glasses. A spin glass is characterized by an ergodic landscape of states - an innumerable number of possibilities that are only weakly distinguished energetically, if at all. We show in the material Fe$_x$NbS$_2$, this landscape of states can be biased by coexisitng antiferromagnetic order. This process leads to a phenomenon of broad technological importance: giant, tunable exchange bias. We observe exchange biases that exceed those of conventional materials by more than two orders of magnitude. This work illustrates a novel route to giant exchange bias by leveraging the interplay of frustration and disorder in exotic materials.

cond-mat.str-el↗

arXiv2017

Correlation-Induced Band Competition in SrTiO3/LaAlO3

The oxide interface SrTiO3/LaAlO3 supports a 2D electron liquid displaying superconductivity and magnetism, while allowing for a continuous control of the electron density using a gate. Our recent measurements have shown a similar surprising nonmonotonic behavior as function of the gate voltage (carrier density) of three quantities: the superconducting critical temperature and field, the inverse Hall coefficient, and the frequency of quantum oscillations. While the total density has to be monotonic as function of gate, the last result indicates that one of the involved bands has a nonmontonic occupancy as function of the chemical potential. We show how electronic interactions can lead to such an effect, by creating a competition between the involved bands and making their structure non-rigid, and thus account for all these effects. Adding Fock terms to our previous Hartree treatment makes this scenario even more generic.

cond-mat.str-el↗