Experimental exploration of novel semimetal state in strong anisotropic Pyrochlore iridate Nd2Ir2O7 under high magnetic field

We report the anisotropic magnetotransport of Nd2Ir2O7 single crystal under high magnetic field (B) up to 50 T with B along various directions. Only for B // [001] direction, a novel semimetal state is realized under high magnetic field evidenced by a field-induced insulating-semimetalic phase transition with critical field B-MI similar to 12 T related to the destruction of all-in-all-out (AIAO) state. In contrast, abnormal magnetotransport hysteresis behavior is observed for B // [111] direction below the metal-insulator transition temperature (T-MI), and magnetotransport reveals the Ir spin structure keep in the AIAO state under high magnetic field with temperature just below T-MI,T- in prospect to realize Weyl semimetal state.