Ytterbium Diarsenide Breaks Time Symmetry in Type I Superconductor
Physicists at the Indian Institute of Science Education and Research (IISER) Bhopal have identified a type I superconductor, ytterbium diantimonide (YbSb2), that spontaneously breaks time-reversal symmetry. Published in Physical Review Letters, the study confirms that this material enters a superconducting state near -272 degrees Celsius and exhibits internal magnetic fields without external influence. This behavior, previously associated only with unconventional type II superconductors, arises from electrons pairing in an 'internally antisymmetric non-unitary triplet' state. The discovery suggests YbSb2 could host gapless Majorana surface modes, potentially offering enhanced protection for quantum information against environmental noise.