scholarly journals Giant, unconventional anomalous Hall effect in the metallic frustrated magnet candidate, KV3Sb5

2020 ◽  
Vol 6 (31) ◽  
pp. eabb6003 ◽  
Author(s):  
Shuo-Ying Yang ◽  
Yaojia Wang ◽  
Brenden R. Ortiz ◽  
Defa Liu ◽  
Jacob Gayles ◽  
...  
Keyword(s):  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Past Research ◽  
Frustrated Magnets ◽  
Range Magnetic Order ◽  
Magnetic Sublattice ◽  
Longitudinal Conductivity ◽  
Order Of Magnitude ◽  
Frustrated Magnet ◽  
Long Range Magnetic Order

The anomalous Hall effect (AHE) is one of the most fundamental phenomena in physics. In the highly conductive regime, ferromagnetic metals have been the focus of past research. Here, we report a giant extrinsic AHE in KV3Sb5, an exfoliable, highly conductive semimetal with Dirac quasiparticles and a vanadium Kagome net. Even without report of long range magnetic order, the anomalous Hall conductivity reaches 15,507 Ω−1 cm−1 with an anomalous Hall ratio of ≈ 1.8%; an order of magnitude larger than Fe. Defying theoretical expectations, KV3Sb5 shows enhanced skew scattering that scales quadratically, not linearly, with the longitudinal conductivity, possibly arising from the combination of highly conductive Dirac quasiparticles with a frustrated magnetic sublattice. This allows the possibility of reaching an anomalous Hall angle of 90° in metals. This observation raises fundamental questions about AHEs and opens new frontiers for AHE and spin Hall effect exploration, particularly in metallic frustrated magnets.

scholarly journals Evolution of spin excitations from bulk to monolayer FeSe

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jonathan Pelliciari ◽  
Seher Karakuzu ◽  
Qi Song ◽  
Riccardo Arpaia ◽  
Abhishek Nag ◽  
...  
Keyword(s):  
Quantum Monte Carlo ◽  
Spin Dynamics ◽  
Spin Fluctuations ◽  
Superconducting Transition ◽  
Pairing Mechanism ◽  
Range Magnetic Order ◽  
X Ray Scattering ◽  
Spin Excitations ◽  
Order Of Magnitude ◽  
Long Range Magnetic Order

AbstractIn ultrathin films of FeSe grown on SrTiO3 (FeSe/STO), the superconducting transition temperature Tc is increased by almost an order of magnitude, raising questions on the pairing mechanism. As in other superconductors, antiferromagnetic spin fluctuations have been proposed to mediate SC making it essential to study the evolution of the spin dynamics of FeSe from the bulk to the ultrathin limit. Here, we investigate the spin excitations in bulk and monolayer FeSe/STO using resonant inelastic x-ray scattering (RIXS) and quantum Monte Carlo (QMC) calculations. Despite the absence of long-range magnetic order, bulk FeSe displays dispersive magnetic excitations reminiscent of other Fe-pnictides. Conversely, the spin excitations in FeSe/STO are gapped, dispersionless, and significantly hardened relative to its bulk counterpart. By comparing our RIXS results with simulations of a bilayer Hubbard model, we connect the evolution of the spin excitations to the Fermiology of the two systems revealing a remarkable reconfiguration of spin excitations in FeSe/STO, essential to understand the role of spin fluctuations in the pairing mechanism.

scholarly journals Emergent long-range magnetic order in ultrathin (111)-oriented LaNiO3 films

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Margaret M. Kane ◽  
Arturas Vailionis ◽  
Lauren J. Riddiford ◽  
Apurva Mehta ◽  
Alpha T. N’Diaye ◽  
...  
Keyword(s):  
Long Range ◽  
Degrees Of Freedom ◽  
Magnetic Order ◽  
Magnetic Ordering ◽  
Anomalous Hall Effect ◽  
X Ray Diffraction ◽  
X Ray ◽  
Range Magnetic Order ◽  
Film Substrate ◽  
Long Range Magnetic Order

AbstractThe emergence of ferromagnetism in materials where the bulk phase does not show any magnetic order demonstrates that atomically precise films can stabilize distinct ground states and expands the phase space for the discovery of materials. Here, the emergence of long-range magnetic order is reported in ultrathin (111) LaNiO3 (LNO) films, where bulk LNO is paramagnetic, and the origins of this phase are explained. Transport and structural studies of LNO(111) films indicate that NiO6 octahedral distortions stabilize a magnetic insulating phase at the film/substrate interface and result in a thickness-dependent metal–insulator transition at t = 8 unit cells. Away from this interface, distortions relax and bulk-like conduction is regained. Synchrotron x-ray diffraction and dynamical x-ray diffraction simulations confirm a corresponding out-of-plane unit-cell expansion at the interface of all films. X-ray absorption spectroscopy reveals that distortion stabilizes an increased concentration of Ni2+ ions. Evidence of long-range magnetic order is found in anomalous Hall effect and magnetoresistance measurements, likely due to ferromagnetic superexchange interactions among Ni2+–Ni3+ ions. Together, these results indicate that long-range magnetic ordering and metallicity in LNO(111) films emerges from a balance among the spin, charge, lattice, and orbital degrees of freedom.

scholarly journals Anomalous Hall effect in magnetite: Universal scaling relation between Hall and longitudinal conductivity in low-conductivity ferromagnets

2008 ◽  
Vol 78 (9) ◽  
Author(s):  
Deepak Venkateshvaran ◽  
Wolfgang Kaiser ◽  
Andrea Boger ◽  
Matthias Althammer ◽  
M. S. Ramachandra Rao ◽  
...  
Keyword(s):  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Scaling Relation ◽  
Universal Scaling ◽  
Longitudinal Conductivity

Anomalous Hall Effect in Frustrated Magnets

2019 ◽  
Vol 61 (9) ◽  
pp. 1622-1626
Author(s):  
V. V. Glushkov ◽  
M. A. Anisimov ◽  
A. V. Bogach ◽  
A. D. Bozhko ◽  
S. V. Demishev ◽  
...  
Keyword(s):  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Frustrated Magnets

QUANTUM FRUSTRATED MAGNETS: FROM THEORY TO EXPERIMENTS

2003 ◽  
Vol 17 (28) ◽  
pp. 5021-5030
Author(s):  
F. MILA
Keyword(s):  
Detailed Analysis ◽  
Long Range ◽  
Magnetic Order ◽  
Quantum Fluctuations ◽  
Square Lattice ◽  
Frustrated Magnets ◽  
Range Magnetic Order ◽  
Long Range Magnetic Order ◽  
New Compounds ◽  
The Way

This paper presents an overview of the properties predicted and in many cases observed in quantum frustrated magnets. The emphasis will be put on two new compounds which have opened the way to a detailed analysis of two aspects of the problem: (i) Li 2 VOSiO 4, a realisation of the J1 - J2 model on the square lattice in which quantum fluctuations stabilise long-range magnetic order; (ii) Cu 2 Te 2 O 5 Br 2, the first system believed to possess low-lying singlet excitations inside a singlet-triplet gap.

scholarly journals Giant anomalous Hall effect from spin-chirality scattering in a chiral magnet

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yukako Fujishiro ◽  
Naoya Kanazawa ◽  
Ryosuke Kurihara ◽  
Hiroaki Ishizuka ◽  
Tomohiro Hori ◽  
...  
Keyword(s):  
Thin Film ◽  
Hall Effect ◽  
Electron Scattering ◽  
Anomalous Hall Effect ◽  
Limited Attention ◽  
Frustrated Magnets ◽  
Magnetic Field Profile ◽  
Crystalline Anisotropy ◽  
New Type ◽  
Skew Scattering

AbstractThe electrical Hall effect can be significantly enhanced through the interplay of the conduction electrons with magnetism, which is known as the anomalous Hall effect (AHE). Whereas the mechanism related to band topology has been intensively studied towards energy efficient electronics, those related to electron scattering have received limited attention. Here we report the observation of giant AHE of electron-scattering origin in a chiral magnet MnGe thin film. The Hall conductivity and Hall angle, respectively, reach $$40,000$$ 40 , 000  Ω−1 cm−1 and $$18$$ 18 % in the ferromagnetic region, exceeding the conventional limits of AHE of intrinsic and extrinsic origins, respectively. A possible origin of the large AHE is attributed to a new type of skew-scattering via thermally excited spin-clusters with scalar spin chirality, which is corroborated by the temperature–magnetic-field profile of the AHE being sensitive to the film-thickness or magneto-crystalline anisotropy. Our results may open up a new platform to explore giant AHE responses in various systems, including frustrated magnets and thin-film heterostructures.

scholarly journals Unconventional Hall effect and its variation with Co-doping in van der Waals Fe3GeTe2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rajeswari Roy Chowdhury ◽  
Samik DuttaGupta ◽  
Chandan Patra ◽  
Oleg A. Tretiakov ◽  
Sudarshan Sharma ◽  
...  
Keyword(s):  
Hall Effect ◽  
Magnetic Materials ◽  
Long Range ◽  
Magnetic Order ◽  
Van Der Waals ◽  
Two Dimensional ◽  
Spintronic Devices ◽  
Co Doping ◽  
Range Magnetic Order ◽  
Long Range Magnetic Order

AbstractTwo-dimensional (2D) van der Waals (vdW) magnetic materials have attracted a lot of attention owing to the stabilization of long range magnetic order down to atomic dimensions, and the prospect of novel spintronic devices with unique functionalities. The clarification of the magnetoresistive properties and its correlation to the underlying magnetic configurations is essential for 2D vdW-based spintronic devices. Here, the effect of Co-doping on the magnetic and magnetotransport properties of Fe3GeTe2 have been investigated. Magnetotransport measurements reveal an unusual Hall effect behavior whose strength was considerably modified by Co-doping and attributed to arise from the underlying complicated spin textures. The present results provide a clue to tailoring of the underlying interactions necessary for the realization of a variety of unconventional spin textures for 2D vdW FM-based spintronics.

scholarly journals Field-Induced Transitions in Highly Frustrated SrHo2O4

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 488 ◽  
Author(s):  
Olga Young ◽  
Geetha Balakrishnan ◽  
Pascal Manuel ◽  
Dmitry Khalyavin ◽  
Andrew Wildes ◽  
...  
Keyword(s):  
Long Range ◽  
Diffuse Scattering ◽  
Magnetic Order ◽  
Competing Interactions ◽  
Geometrically Frustrated ◽  
Range Magnetic Order ◽  
Ferromagnetic Structure ◽  
Frustrated Magnet ◽  
Long Range Magnetic Order ◽  
Crystallographic Axes

SrHo 2O 4 is a geometrically frustrated magnet in which the magnetic Ho 3 + ions are connected through a network of zigzag chains and coupled by several competing interactions. The Ho 3 + ions show a pronounced Ising anisotropy at low temperatures, and the spins on the two crystallographically inequivalent magnetic sites point along orthogonal crystallographic axes. Using single-crystal neutron diffraction, we report on the development of complex and highly anisotropic short- and long-range magnetic order in SrHo 2O 4 induced by an applied magnetic field. For H ‖ c , the diffuse scattering around the k = 0 positions is suppressed and above 0.5 T the spin structure for one of the Ho sites is long-range and ferromagnetic. For H ‖ b , planes of diffuse scattering at Q = ( h k ± l 2 ) are split by the field, and an up–up–down magnetic order associated with a 1/3-magnetisation plateau develops at 0.8 T. Further increasing the field above 1.2 T allows the second Ho site to also order in a long-range ferromagnetic structure.

Anomaly in the Hall Ooefficient of Ag/Cr Superlattices

1991 ◽  
Vol 229 ◽  
Author(s):  
Hideyuki Sato ◽  
Tadashi Kumano ◽  
Takeo Kaneko ◽  
Ryoichi Yamamoto
Keyword(s):  
Hall Effect ◽  
Layer Thickness ◽  
Long Range ◽  
Field Dependence ◽  
Hall Coefficient ◽  
Magnetic Order ◽  
Absolute Value ◽  
Range Magnetic Order ◽  
Negative Peak ◽  
Long Range Magnetic Order

AbstractThe Hall effect on Ag/Cr superlattice system has been investigated. When the Cr layer thickness is changed from 1 monolayer (ML) to 6ML for the same Ag layer thickness of 10 ML, the Hall coefficient (RH) varies anomalously. For 1 ML Cr sample, we obtained RH value close to that of pure Ag as expected. The absolute value of RH is enhanced with increasing Cr layer thickness. After having a negative peak near 3 ML Cr, it decreases at larger Cr thicknesses. The field dependence of the Hall resistivity is linear for all the samples, and there is no sign of long range magnetic order down to 1.5K.

Room Temperature Ferromagnetism in Gadolinium-doped Gallium Nitride

MRS Advances ◽  
2018 ◽  
Vol 3 (3) ◽  
pp. 159-164 ◽  
Author(s):  
Vishal G. Saravade ◽  
Cameron H. Ferguson ◽  
Amirhossein Ghods ◽  
Chuanle Zhou ◽  
Ian T. Ferguson
Keyword(s):  
Magnetic Properties ◽  
Gallium Nitride ◽  
Hall Effect ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Organic Ligand ◽  
Anomalous Hall Effect ◽  
Longitudinal Conductivity ◽  
Metallic Conduction ◽  
The Relationship

ABSTRACTAnomalous Hall effect was observed at room temperature in MOCVD-grown GaGdN from a (TMHD)3Gd source, which can contain oxygen in its organic ligand. GaN, and GaGdN grown using a Cp3Gd precursor which does not contain oxygen only showed the ordinary Hall effect. This indicates that oxygen could have a role in magnetic properties of GaGdN. The relationship between the anomalous Hall conductivity and longitudinal conductivity indicated that metallic conduction, hopping of carriers, and scattering-independent mechanisms are likely responsible for the ferromagnetism. However, this still requires further clarification.

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