Month: March 2024

A publication with Jairo Sinova, Libor Šmejkal, Anna B. Hellenes, Rodrigo Jaeschke Ubiergo and Venkata K. Bharadwaj about supercell altermagnets has been published in Physical Review B.

They substantially broaden the family of altermagnetic candidates by predicting supercell altermagnets. Their magnetic unit cell is constructed by enlarging the nonmagnetic primitive unit cell, resulting in a nonzero propagation vector for the magnetic structure. This connection of the magnetic configuration to the ordering of sublattices gives an extra degree of freedom to supercell altermagnets, which can allow for the control over the order parameter spatial orientation. They identify realistic candidates ${\mathrm{MnSe}}_2$ with a $d$-wave order, and ${\mathrm{RbCoBr}}_3,{\mathrm{CsCoCr}}_3$, and ${\mathrm{BaMnO}}_3$ with $g$-wave order. They demonstrate the reorientation of the order parameter in ${\mathrm{MnSe}}_2$, which has two different magnetic configurations, whose energy difference is only 5 meV, opening the possibility of controlling the orientation of the altermagnetic order parameter by external perturbations.

A joint publication with Jairo Sinova, Libor Šmejkal, Anna B. Hellenes, Rodrigo Jaeschke Ubiergo, Warlley H. Campos, Venkata K. Bharadwaj and Atasi Chakraborty about the direct observation of altermagnetic band splitting in CrSb thin films has been published in Nature Communications.

They investigate directly this unconventional band splitting near the Fermi energy through spin-integrated soft X-ray angular resolved photoemission spectroscopy. The experimentally obtained angle-dependent photoemission intensity, acquired from epitaxial thin films of the predicted altermagnet CrSb, demonstrates robust agreement with the corresponding band structure calculations. In particular, they observe the distinctive splitting of an electronic band on a low-symmetry path in the Brilliouin zone that connects two points featuring symmetry-induced degeneracy. The measured large magnitude of the spin splitting of approximately 0.6 eV and the position of the band just below the Fermi energy underscores the significance of altermagnets for spintronics based on robust broken time reversal symmetry responses arising from exchange energy scales, akin to ferromagnets, while remaining insensitive to external magnetic fields and possessing THz dynamics, akin to antiferromagnets.