Magnetically Controllable Cooperative Jahn-Teller Distortion in TmAsO4

Abstract
TmAsO4 undergoes a cooperative Jahn-Teller distortion at 6.0 K. At T<6 K there is a temperature-dependent critical field Bc at which a cooperative distortion back to the high-temperature phase occurs. For B<Bc, the distortion directions in the basal plane are the (110) and the (11¯0) directions and are magnetically controllable.