3 research outputs found
Direct observation of altermagnetic band splitting in CrSb thin films
Altermagnetism represents an emergent collinear magnetic phase with
compensated order and an unconventional alternating even-parity wave spin order
in the non-relativistic band structure. We investigate directly this
unconventional band splitting near the Fermi energy through spinintegrated 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, we 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
signifcance 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.Comment: 10 pages, 7 figures (including supplementary information
Observation of time-reversal symmetry breaking in the band structure of altermagnetic RuO 2
Altermagnets are an emerging elementary class of collinear magnets. Unlike ferromagnets, their distinct crystal symmetries inhibit magnetization while, unlike antiferromagnets, they promote strong spin polarization in the band structure. The corresponding unconventional mechanism of time-reversal symmetry breaking without magnetization in the electronic spectra has been regarded as a primary signature of altermagnetism but has not been experimentally visualized to date. We directly observe strong time-reversal symmetry breaking in the band structure of altermagnetic RuO2 by detecting magnetic circular dichroism in angle-resolved photoemission spectra. Our experimental results, supported by ab initio calculations, establish the microscopic electronic structure basis for a family of interesting phenomena and functionalities in fields ranging from topological matter to spintronics, which are based on the unconventional time-reversal symmetry breaking in altermagnets