Chiral Soliton Lattice Formation in Monoaxial Helimagnet Yb(Ni$_{1-x}$Cu$_x$)$_3$Al$_9$

TL;DR

This study reveals the formation of a chiral magnetic soliton lattice in Yb(Ni$_{1-x}$Cu$_x$)$_3$Al$_9$, demonstrating the influence of crystal chirality on magnetic helicity and observing higher harmonic peaks indicative of complex magnetic states.

Contribution

It provides experimental evidence for chiral magnetic soliton lattice formation and links crystal chirality to magnetic helicity via resonant X-ray diffraction.

Findings

Chiral magnetic soliton lattice state confirmed by higher harmonic peaks.

Crystal chirality directly influences magnetic helicity.

Observation of magnetic octupole moments alongside dipole order.

Abstract

Helical magnetic structures and its responses to external magnetic fields in Yb(Ni$_x$Cu$_{1-x}$)$_3$Al$_9$, with a chiral crystal structure of the space group $R32$, have been investigated by resonant X-ray diffraction. It is shown that the crystal chirality is reflected to the helicity of the magnetic structure by a one to one relationship, indicating that there exists an antisymmetric exchange interaction mediated via the conduction electrons. When a magnetic field is applied perpendicular to the helical axis ($c$ axis), the second harmonic peak of $(0, 0, 2q)$ develops with increasing the field. The third harmonic peak of $(0, 0, 3q)$ has also been observed for the $x$=0.06 sample. This result provides a strong evidence for the formation of a chiral magnetic soliton lattice state, a periodic array of the chiral twist of spins, which has been suggested by the characteristic magnetization curve. The helical ordering of magnetic octupole moments, accompanying with the magnetic dipole order, has also been detected.