Field-tuned Collapse of an Orbital Ordered and Spin-polarized State: Colossal Magnetoresistance in Bilayered Ruthenate

TL;DR

This study demonstrates that applying magnetic fields along different axes in Ca3Ru2O7 causes a colossal reduction in resistivity by collapsing an orbital ordered and spin-polarized state, revealing anisotropic magnetoresistance behavior.

Contribution

It shows how magnetic field orientation controls the collapse of orbital and spin order, leading to colossal magnetoresistance in bilayered ruthenate, a novel insight into its electronic phase transitions.

Findings

Magnetic field along easy axis induces spin polarization without full Mott state suppression.

Magnetic field along hard axis causes resistivity to drop by three orders of magnitude.

Evidence suggests the presence of a density wave in the material.

Abstract

Ca3Ru2O7 with a Mott-like transition at 48 K features different in-plane anisotropies of magnetization and magnetoresistance. Applying magnetic field along the magnetic easy-axis precipitates a spin-polarized state via a first-order metamagnetic transition, but does not lead to a full suppression of the Mott state, whereas applying magnetic field along the magnetic hard axis does, causing a resistivity reduction of three orders of magnitude. The colossal magnetoresistivity is attributed to the collapse of the orbital ordered and spin-polarized state. Evidence for a density wave is also presented.