Spin-glass behavior in the antiperovskite manganese nitride codoped with Ge and Si

Antiperovskite manganese nitrides Mn 3 ( Cu 0.6 Si x Ge 0.4 − x ) N ( x = 0.05 , 0.1, 0.15) were prepared and their negative thermal expansion, magnetic and specific heat properties were investigated. A frozen state with a freezing temperature was found at ∼207 K in Mn 3 ( Cu 0.6 Si 0.15 Ge 0.25 ) N . This indicates that Mn 3 ( Cu 0.6 Si 0.15 Ge 0.25 ) N exhibits a spin glass state at low temperatures. We discussed the cause of spin glass behavior and correlated this spin glass behavior with broadening of the negative thermal expansion operation-temperature window of the manganese nitrides Mn 3 ( Cu 0.6 Si 0.15 Ge 0.25 ) N .