Photo-creating supercooled spiral-spin states in a multiferroic manganite

TL;DR

This study demonstrates optical control of spiral-spin states in a multiferroic manganite, revealing supercooling-induced metastable states and photo-switching between different multiferroic phases with potential for novel optoelectronic applications.

Contribution

It introduces a method to optically induce and stabilize supercooled spiral-spin states in a multiferroic material, showcasing a new way to manipulate complex magnetic orders.

Findings

Supercooled bc-spiral-spin state can be photoinduced in Eu0.55Y0.45MnO3.

Metastable states exhibit prolonged lifetimes dependent on magnetic field.

Optical switching between ab- and bc-spiral phases demonstrated.

Abstract

We demonstrate that dynamics of the ab-spiral-spin order in a magnetoelectric multiferroic Eu0.55Y0.45MnO3 can be unambiguously probed through optical second harmonic signals, generated via the spin-induced ferroelectric polarization. In the case of relatively weak photoexcitation,the ferroelectric and the spiral-spin order remains interlocked, both relaxing through spin-lattice relaxation in the non-equilibrium state. When the additional optical pulse illuminating sample is intense enough to induced a local phase transition thermally, the system creates a metastable state of the bc-spiral-spin order (with the electric polarization P//c) via supercooling across the first-order phase transition between ab- and bc-spiral. The supercooled state of bc-spiral spin is formed in the thermodynamical ground state of ab-spiral (P//a), displaying a prolonged lifetime with strong dependence on the magnetic field along the a-axis. The observed photo-switching between the two distinct multiferroic states sheds light on novel photoinduced phenomena in spiral-spin multiferroics.