Colossal magnetoresistance in a Mott insulator via magnetic field-driven insulator-metal transition

TL;DR

This paper reports a novel colossal magnetoresistance effect in a Mott insulator caused by a magnetic field-induced insulator-metal transition, involving lattice and magnetic structure changes in a bilayer ruthenate.

Contribution

It reveals a new CMR mechanism in a Mott insulator driven by magnetic fields, challenging existing understanding and suggesting new material search directions.

Findings

Magnetic field induces insulator-metal transition in Ti-doped Ca3Ru2O7

Transition involves coupled lattice and magnetic structure changes

Provides a model for CMR in Mott insulators near phase boundaries

Abstract

We present a new type of colossal magnetoresistance (CMR) arising from an anomalous collapse of the Mott insulating state via a modest magnetic field in a bilayer ruthenate, Ti-doped Ca$_3$Ru$_2$O$_7$. Such an insulator-metal transition is accompanied by changes in both lattice and magnetic structures. Our findings have important implications because a magnetic field usually stabilizes the insulating ground state in a Mott-Hubbard system, thus calling for a deeper theoretical study to reexamine the magnetic field tuning of Mott systems with magnetic and electronic instabilities and spin-lattice-charge coupling. This study further provides a model approach to search for CMR systems other than manganites, such as Mott insulators in the vicinity of the boundary between competing phases.