scholarly journals Time-reversal symmetry breaking and spontaneous anomalous Hall effect in Fermi fluids

2008 ◽  
Vol 78 (24) ◽  
Author(s):  
Kai Sun ◽  
Eduardo Fradkin
Keyword(s):  
Symmetry Breaking ◽  
Hall Effect ◽  
Time Reversal ◽  
Anomalous Hall Effect ◽  
Time Reversal Symmetry ◽  
Fermi Fluids

scholarly journals Crystal time-reversal symmetry breaking and spontaneous Hall effect in collinear antiferromagnets

2020 ◽  
Vol 6 (23) ◽  
pp. eaaz8809 ◽  
Author(s):  
Libor Šmejkal ◽  
Rafael González-Hernández ◽  
T. Jungwirth ◽  
J. Sinova
Keyword(s):  
Symmetry Breaking ◽  
Hall Effect ◽  
Time Reversal ◽  
Spin Structure ◽  
Transverse Velocity ◽  
Time Reversal Symmetry ◽  
Large Magnitude ◽  
Low Dissipation ◽  
Magnetization Density ◽  
Symmetry Breaking Phenomena

Electrons, commonly moving along the applied electric field, acquire in certain magnets a dissipationless transverse velocity. This spontaneous Hall effect, found more than a century ago, has been understood in terms of the time-reversal symmetry breaking by the internal spin structure of a ferromagnetic, noncolinear antiferromagnetic, or skyrmionic form. Here, we identify previously overlooked robust Hall effect mechanism arising from collinear antiferromagnetism combined with nonmagnetic atoms at noncentrosymmetric positions. We predict a large magnitude of this crystal Hall effect in a room temperature collinear antiferromagnet RuO2 and catalog, based on symmetry rules, extensive families of material candidates. We show that the crystal Hall effect is accompanied by the possibility to control its sign by the crystal chirality. We illustrate that accounting for the full magnetization density distribution instead of the simplified spin structure sheds new light on symmetry breaking phenomena in magnets and opens an alternative avenue toward low-dissipation nanoelectronics.

scholarly journals Giant spontaneous Hall effect in a nonmagnetic Weyl–Kondo semimetal

2021 ◽  
Vol 118 (8) ◽  
pp. e2013386118 ◽  
Author(s):  
Sami Dzsaber ◽  
Xinlin Yan ◽  
Mathieu Taupin ◽  
Gaku Eguchi ◽  
Andrey Prokofiev ◽  
...  
Keyword(s):  
Hall Effect ◽  
Time Reversal ◽  
Anomalous Hall Effect ◽  
Time Reversal Symmetry ◽  
Strong Electron ◽  
Band Theory ◽  
Fermion Systems ◽  
Topological Quantum ◽  
Interacting Systems ◽  
Nontrivial Topology

Nontrivial topology in condensed-matter systems enriches quantum states of matter to go beyond either the classification into metals and insulators in terms of conventional band theory or that of symmetry-broken phases by Landau’s order parameter framework. So far, focus has been on weakly interacting systems, and little is known about the limit of strong electron correlations. Heavy fermion systems are a highly versatile platform to explore this regime. Here we report the discovery of a giant spontaneous Hall effect in the Kondo semimetal Ce3Bi4Pd3 that is noncentrosymmetric but preserves time-reversal symmetry. We attribute this finding to Weyl nodes—singularities of the Berry curvature—that emerge in the immediate vicinity of the Fermi level due to the Kondo interaction. We stress that this phenomenon is distinct from the previously detected anomalous Hall effect in materials with broken time-reversal symmetry; instead, it manifests an extreme topological response that requires a beyond-perturbation-theory description of the previously proposed nonlinear Hall effect. The large magnitude of the effect in even tiny electric and zero magnetic fields as well as its robust bulk nature may aid the exploitation in topological quantum devices.

Time-reversal symmetry breaking and spontaneous Hall effect without magnetic dipole order

Nature ◽  
2009 ◽  
Vol 463 (7278) ◽  
pp. 210-213 ◽  
Author(s):  
Yo Machida ◽  
Satoru Nakatsuji ◽  
Shigeki Onoda ◽  
Takashi Tayama ◽  
Toshiro Sakakibara
Keyword(s):  
Symmetry Breaking ◽  
Hall Effect ◽  
Magnetic Dipole ◽  
Time Reversal ◽  
Time Reversal Symmetry

scholarly journals Giant c-axis nonlinear anomalous Hall effect in Td-MoTe2 and WTe2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Archana Tiwari ◽  
Fangchu Chen ◽  
Shazhou Zhong ◽  
Elizabeth Drueke ◽  
Jahyun Koo ◽  
...  
Keyword(s):  
Hall Effect ◽  
Time Reversal ◽  
Low Temperatures ◽  
Magnetic Order ◽  
Anomalous Hall Effect ◽  
Time Reversal Symmetry ◽  
Inversion Center ◽  
Scattering Process ◽  
Berry Curvature ◽  
Skew Scattering

AbstractWhile the anomalous Hall effect can manifest even without an external magnetic field, time reversal symmetry is nonetheless still broken by the internal magnetization of the sample. Recently, it has been shown that certain materials without an inversion center allow for a nonlinear type of anomalous Hall effect whilst retaining time reversal symmetry. The effect may arise from either Berry curvature or through various asymmetric scattering mechanisms. Here, we report the observation of an extremely large c-axis nonlinear anomalous Hall effect in the non-centrosymmetric Td phase of MoTe2 and WTe2 without intrinsic magnetic order. We find that the effect is dominated by skew-scattering at higher temperatures combined with another scattering process active at low temperatures. Application of higher bias yields an extremely large Hall ratio of E⊥/E|| = 2.47 and corresponding anomalous Hall conductivity of order 8 × 107 S/m.

scholarly journals Unsplit superconducting and time reversal symmetry breaking transitions in Sr2RuO4 under hydrostatic pressure and disorder

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Vadim Grinenko ◽  
Debarchan Das ◽  
Ritu Gupta ◽  
Bastian Zinkl ◽  
Naoki Kikugawa ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Symmetry Breaking ◽  
Time Reversal ◽  
Order Parameter ◽  
Muon Spin Rotation ◽  
Horizontal Line ◽  
Time Reversal Symmetry ◽  
Zero Field ◽  
Symmetry Protected ◽  
Line Node

AbstractThere is considerable evidence that the superconducting state of Sr2RuO4 breaks time reversal symmetry. In the experiments showing time reversal symmetry breaking, its onset temperature, TTRSB, is generally found to match the critical temperature, Tc, within resolution. In combination with evidence for even parity, this result has led to consideration of a dxz ± idyz order parameter. The degeneracy of the two components of this order parameter is protected by symmetry, yielding TTRSB = Tc, but it has a hard-to-explain horizontal line node at kz = 0. Therefore, s ± id and d ± ig order parameters are also under consideration. These avoid the horizontal line node, but require tuning to obtain TTRSB ≈ Tc. To obtain evidence distinguishing these two possible scenarios (of symmetry-protected versus accidental degeneracy), we employ zero-field muon spin rotation/relaxation to study pure Sr2RuO4 under hydrostatic pressure, and Sr1.98La0.02RuO4 at zero pressure. Both hydrostatic pressure and La substitution alter Tc without lifting the tetragonal lattice symmetry, so if the degeneracy is symmetry-protected, TTRSB should track changes in Tc, while if it is accidental, these transition temperatures should generally separate. We observe TTRSB to track Tc, supporting the hypothesis of dxz ± idyz order.

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