scholarly journals Quantum materials with strong spin-orbit coupling: challenges and opportunities for materials chemists

Author(s):  
Alexander J. Browne ◽  
Aleksandra Krajewska ◽  
Alexandra Gibbs

Spin-orbit coupling is a quantum effect that can give rise to exotic electronic and magnetic states in the compounds of the 4d and 5d transition metals. Exploratory synthesis, chemical tuning...

SPIN ◽  
2016 ◽  
Vol 06 (02) ◽  
pp. 1640002 ◽  
Author(s):  
Jacob Torrejon ◽  
Junyeon Kim ◽  
Jaivardhan Sinha ◽  
Masamitsu Hayashi

We study effects originating from the strong spin–orbit coupling in CoFeB/MgO heterostructures with heavy metal (HM) underlayers. The perpendicular magnetic anisotropy at the CoFeB/MgO interface, the spin Hall angle of the heavy metal layer, current induced torques and the Dzyaloshinskii–Moriya interaction at the HM/CoFeB interfaces are studied for films in which the early 5[Formula: see text] transition metals are used as the HM underlayer. We show how the choice of the HM layer influences these intricate spin–orbit effects that emerge within the bulk and at interfaces of the heterostructures.


2019 ◽  
Vol 116 (10) ◽  
pp. 4006-4011 ◽  
Author(s):  
H.-H. Kung ◽  
A. P. Goyal ◽  
D. L. Maslov ◽  
X. Wang ◽  
A. Lee ◽  
...  

The protected electron states at the boundaries or on the surfaces of topological insulators (TIs) have been the subject of intense theoretical and experimental investigations. Such states are enforced by very strong spin–orbit interaction in solids composed of heavy elements. Here, we study the composite particles—chiral excitons—formed by the Coulomb attraction between electrons and holes residing on the surface of an archetypical 3D TI,Bi2Se3. Photoluminescence (PL) emission arising due to recombination of excitons in conventional semiconductors is usually unpolarized because of scattering by phonons and other degrees of freedom during exciton thermalization. On the contrary, we observe almost perfectly polarization-preserving PL emission from chiral excitons. We demonstrate that the chiral excitons can be optically oriented with circularly polarized light in a broad range of excitation energies, even when the latter deviate from the (apparent) optical band gap by hundreds of millielectronvolts, and that the orientation remains preserved even at room temperature. Based on the dependences of the PL spectra on the energy and polarization of incident photons, we propose that chiral excitons are made from massive holes and massless (Dirac) electrons, both with chiral spin textures enforced by strong spin–orbit coupling. A theoretical model based on this proposal describes quantitatively the experimental observations. The optical orientation of composite particles, the chiral excitons, emerges as a general result of strong spin–orbit coupling in a 2D electron system. Our findings can potentially expand applications of TIs in photonics and optoelectronics.


2020 ◽  
Vol 117 (24) ◽  
pp. 242402
Author(s):  
R. Ramos ◽  
T. Makiuchi ◽  
T. Kikkawa ◽  
S. Daimon ◽  
K. Oyanagi ◽  
...  

2018 ◽  
Vol 98 (20) ◽  
Author(s):  
Mai Ye ◽  
Heung-Sik Kim ◽  
Jae-Wook Kim ◽  
Choong-Jae Won ◽  
Kristjan Haule ◽  
...  

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