Emergent 1/3 magnetization plateaus in pyroxene CoGeO$_3$

TL;DR

This study reveals the unexpected presence of well-defined 1/3 magnetization plateaus in CoGeO$_3$, a pyroxene mineral, and uncovers their microscopic spin structure using neutron diffraction, proposing a new frustrated lattice model.

Contribution

The paper demonstrates the emergence of 1/3 magnetization plateaus in CoGeO$_3$ and provides a detailed microscopic spin structure analysis, introducing a novel frustrated lattice model.

Findings

Observation of 1/3 magnetization plateaus in CoGeO$_3$

Identification of a modulated magnetic structure with a 1/3 propagation vector

Proposal of a microscopic model based on an anisotropic frustrated square lattice

Abstract

Despite the absence of an apparent triangular pattern in the crystal structure, we observe unusually well pronounced 1/3 magnetization plateaus in the quasi one-dimensional Ising spin chain compound CoGeO$_3$ which belongs to the class of pyroxene minerals. We succeeded in uncovering the detailed microscopic spin structure of the 1/3 magnetization plateau phase by means of neutron diffraction. We observed changes of the initial antiferromagnetic zero-field spin structure that are resembling a regular formation of antiferromagnetic "domain wall boundaries", resulting in a kind of modulated magnetic structure with 1/3-integer propagation vector. The net ferromagnetic moment emerges at these "domain walls" whereas two third of all antiferromagnetic chain alignments can be still preserved. We propose a microscopic model on the basis of an anisotropic frustrated square lattice to explain the observations.