scholarly journals Electronically driven spin-reorientation transition of the correlated polar metal Ca3Ru2O7

2020 ◽  
Vol 117 (27) ◽  
pp. 15524-15529 ◽  
Author(s):  
Igor Marković ◽  
Matthew D. Watson ◽  
Oliver J. Clark ◽  
Federico Mazzola ◽  
Edgar Abarca Morales ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Sudden Onset ◽  
Spin Reorientation ◽  
Orbit Coupling ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Large Hole ◽  
Electronic Correlations ◽  
Spin Reorientation Transition

The interplay between spin–orbit coupling and structural inversion symmetry breaking in solids has generated much interest due to the nontrivial spin and magnetic textures which can result. Such studies are typically focused on systems where large atomic number elements lead to strong spin–orbit coupling, in turn rendering electronic correlations weak. In contrast, here we investigate the temperature-dependent electronic structure ofCa3Ru2O7, a4doxide metal for which both correlations and spin–orbit coupling are pronounced and in which octahedral tilts and rotations combine to mediate both global and local inversion symmetry-breaking polar distortions. Our angle-resolved photoemission measurements reveal the destruction of a large hole-like Fermi surface upon cooling through a coupled structural and spin-reorientation transition at 48 K, accompanied by a sudden onset of quasiparticle coherence. We demonstrate how these result from band hybridization mediated by a hidden Rashba-type spin–orbit coupling. This is enabled by the bulk structural distortions and unlocked when the spin reorients perpendicular to the local symmetry-breaking potential at the Ru sites. We argue that the electronic energy gain associated with the band hybridization is actually the key driver for the phase transition, reflecting a delicate interplay between spin–orbit coupling and strong electronic correlations and revealing a route to control magnetic ordering in solids.

Huge Rashba-type spin–orbit coupling in binary hexagonal PX nanosheets (X = As, Sb, and Bi)

2018 ◽  
Vol 20 (48) ◽  
pp. 30133-30139 ◽  
Author(s):  
Liyan Zhu ◽  
Tingting Zhang ◽  
Guibin Chen ◽  
Huabao Chen
Keyword(s):  
Symmetry Breaking ◽  
Orbit Coupling ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit

Inversion symmetry breaking in binary alloyed hexagonal PX nanosheets (X = As, Sb, and Bi) results in a huge Rashba-type spin–orbit coupling.

scholarly journals Dzyaloshinskii–Moriya interaction in noncentrosymmetric superlattices

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Woo Seung Ham ◽  
Abdul-Muizz Pradipto ◽  
Kay Yakushiji ◽  
Kwangsu Kim ◽  
Sonny H. Rhim ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Degrees Of Freedom ◽  
Orbit Coupling ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Band Formation ◽  
Research Activities ◽  
Moriya Interaction

AbstractDzyaloshinskii–Moriya interaction (DMI) is considered as one of the most important energies for specific chiral textures such as magnetic skyrmions. The keys of generating DMI are the absence of structural inversion symmetry and exchange energy with spin–orbit coupling. Therefore, a vast majority of research activities about DMI are mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report an asymmetric band formation in a superlattices (SL) which arises from inversion symmetry breaking in stacking order of atomic layers, implying the role of bulk-like contribution. Such bulk DMI is more than 300% larger than simple sum of interfacial contribution. Moreover, the asymmetric band is largely affected by strong spin–orbit coupling, showing crucial role of a heavy metal even in the non-interfacial origin of DMI. Our work provides more degrees of freedom to design chiral magnets for spintronics applications.

scholarly journals Giant Dzyaloshinskii-Moriya interaction in Rashba superlattices

2020 ◽  
Author(s):  
Woo-Seung Ham ◽  
Abdul-Muizz Pradipto ◽  
Kay Yakushiji ◽  
Kwangsu Kim ◽  
Sonny Rhim ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Material Design ◽  
Orbit Coupling ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Band Formation ◽  
Stacking Order ◽  
Magnetic Skyrmions ◽  
Moriya Interaction

Abstract Dzyaloshinskii-Moriya interaction (DMI) is considered as one of the most important energy for specific chiral texture such as magnetic skyrmions. The key of generating DMI is absence of structural inversion symmetry and exchange energy with spin-orbit coupling. Therefore, a vast majority of researches about DMI is mainly limited to heavy metal/ferromagnet bilayer systems, only focusing on their interfaces. Here, we report that asymmetric band formation in an artificial superlattice arises from inversion symmetry breaking in stacking order of atomic layers, resulting in bulk DMI. Such bulk DMI is more than 300% larger than simple sum of interfacial contribution. Moreover, the asymmetric band is largely affected by strong spin-orbit coupling, showing crucial role of a heavy metal even in the non-interfacial origin of DMI. Such Rashba superlattices can be a new class of material design for spintronics applications.

scholarly journals Absence of the Rashba Splitting of Au(111) Surface Bands

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
I. N. Yakovkin
Keyword(s):  
Electronic Structure ◽  
Dft Calculations ◽  
Surface States ◽  
Orbit Coupling ◽  
Spin Splitting ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Relativistic Approximation ◽  
Photoemission Experiment

The electronic structure of Au(111) films is studied by means of relativistic DFT calculations. It is found that the twinning of the surface bands, observed in photoemission experiment, does not necessarily correspond to the spin-splitting of the surface states caused by the break of the inversion symmetry at the surface. The twinning of the bands of clean Au(111) films can be obtained within nonrelativistic or scalar-relativistic approximation, so that it is not a result of spin-orbit coupling. However, the spin-orbit coupling does not lead to the spin-splitting of the surface bands. This result is explained by Kramers’ degeneracy, which means that the existence of a surface itself does not destroy the inversion symmetry of the system. The inversion symmetry of the Au(111) film can be broken, for example, by means of adsorption, and a hydrogen monolayer deposited on one face of the film indeed leads to the appearance of the spin-splitting of the bands.

scholarly journals Type-II Ising pairing in few-layer stanene

Science ◽  
2020 ◽  
Vol 367 (6485) ◽  
pp. 1454-1457 ◽  
Author(s):  
Joseph Falson ◽  
Yong Xu ◽  
Menghan Liao ◽  
Yunyi Zang ◽  
Kejing Zhu ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Upper Critical Field ◽  
Distinct Type ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Type Ii ◽  
Spin Orbit ◽  
Pairing Mechanism ◽  
Topological Materials ◽  
Ultralow Temperature

Spin-orbit coupling has proven indispensable in the realization of topological materials and, more recently, Ising pairing in two-dimensional superconductors. This pairing mechanism relies on inversion symmetry–breaking and sustains anomalously large in-plane polarizing magnetic fields whose upper limit is predicted to diverge at low temperatures. Here, we show that the recently discovered superconductor few-layer stanene, epitaxially strained gray tin (α-Sn), exhibits a distinct type of Ising pairing between carriers residing in bands with different orbital indices near the Γ-point. The bands are split as a result of spin-orbit locking without the participation of inversion symmetry–breaking. The in-plane upper critical field is strongly enhanced at ultralow temperature and reveals the predicted upturn.

scholarly journals Theory of optical responses in clean multi-band superconductors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Junyeong Ahn ◽  
Naoto Nagaosa
Keyword(s):  
Pairing Symmetry ◽  
Orbit Coupling ◽  
Optical Measurements ◽  
Inversion Symmetry ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Clean Limit ◽  
Optical Responses ◽  
Optical Excitations ◽  
Multi Band

AbstractElectromagnetic responses in superconductors provide valuable information on the pairing symmetry as well as physical quantities such as the superfluid density. However, at the superconducting gap energy scale, optical excitations of the Bogoliugov quasiparticles are forbidden in conventional Bardeen-Cooper-Schrieffer superconductors when momentum is conserved. Accordingly, far-infrared optical responses have been understood in the framework of a dirty-limit theory by Mattis and Bardeen for over 60 years. Here we show, by investigating the selection rules imposed by particle-hole symmetry and unitary symmetries, that intrinsic momentum-conserving optical excitations can occur in clean multi-band superconductors when one of the following three conditions is satisfied: (i) inversion symmetry breaking, (ii) symmetry protection of the Bogoliubov Fermi surfaces, or (iii) simply finite spin-orbit coupling with unbroken time reversal and inversion symmetries. This result indicates that clean-limit optical responses are common beyond the straightforward case of broken inversion symmetry. We apply our theory to optical responses in FeSe, a clean multi-band superconductor with inversion symmetry and significant spin-orbit coupling. This result paves the way for studying clean-limit superconductors through optical measurements.

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