Magnetization and Hall effect studies on the pyrochlore iridate Nd2Ir2O7

TL;DR

This study investigates the magnetic and Hall effect properties of Nd2Ir2O7, revealing complex magnetic transitions, hysteresis, and anomalous Hall effects indicative of spin reorientation and non-trivial magnetic states.

Contribution

It provides new experimental insights into the magnetic phases and Hall effects in Nd2Ir2O7, highlighting a possible spin reorientation transition across the metal-insulator boundary.

Findings

Observation of remnant magnetization below T_M

Hysteresis and anomalous Hall effect at low temperatures

Evidence of spin reorientation transition

Abstract

We present magnetization and Hall effect measurements on the pyrochlore iridate Nd2Ir2O7. Previous muon spin rotation measurements have shown that the system undergoes an unusual transition at T$_M$ = 110 K into a magnetic phase lacking long-range order, followed by a transition at T$_LRO$ = 6 K into a state with long-range magnetic order. We observe a small remnant magnetization when cycling through zero magnetic field at temperatures below T$_M$. Below T$_LRO$, this remnant magnetization increases sharply, and new hysteresis effects appear at a higher field B$_c$ = 2.5 T, while the Hall resistance develops a non-monotonic and hysteretic magnetic field dependence, with a maximum at B$_c$ and signatures of an anomalous Hall effect. The dependence on field sweep direction demonstrates a non-trivial transition into a magnetically ordered state with properties paralleling those of known spin-ice systems and suggests a spin reorientation transition across the metal insulator transition in the A-227 series.