Observation of distorted tilted conical phase at the surface of a bulk chiral magnet with resonant elastic x-ray scattering

TL;DR

This study reveals a stable, distorted tilted conical spiral surface phase in Cu$_2$OSeO$_3$ with unique magnetic features, coexisting with skyrmions, observed via resonant elastic X-ray scattering at low temperatures.

Contribution

First observation of a distorted tilted conical spiral surface phase in a bulk chiral magnet using resonant elastic X-ray scattering.

Findings

Identified a stable surface phase called the distorted tilted conical spiral.

Detected coexistence of skyrmions with the surface phase.

The surface phase persists through magnetic field cycling until high fields induce a polarized state.

Abstract

We report on various magnetic configurations including spirals and skyrmions at the surface of the magnetic insulator Cu$_2$OSeO$_3$ at low temperatures with a magnetic field applied along <100> using resonant elastic X-ray scattering (REXS). We observe a well-ordered surface state referred to as a distorted tilted conical spiral (TC) phase over a wide range of magnetic fields. The distorted TC phase shows characteristic higher harmonic magnetic satellites in the REXS reciprocal space maps. Skyrmions emerge following static magnetic field cycling and appear to coexist with the distorted TC phase. Our results indicate that this phase represents a distinct and stable surface state that does not disappear with field cycling and persists until the field strength is increased sufficiently to create the field-polarized state.