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 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 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.

scholarly journals Time-reversal symmetry breaking superconducting ground state in the doped Mott insulator on the honeycomb lattice

2013 ◽  
Vol 88 (15) ◽  
Author(s):  
Zheng-Cheng Gu ◽  
Hong-Chen Jiang ◽  
D. N. Sheng ◽  
Hong Yao ◽  
Leon Balents ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Ground State ◽  
Time Reversal ◽  
Mott Insulator ◽  
Honeycomb Lattice ◽  
Time Reversal Symmetry ◽  
Doped Mott Insulator
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