Complex itinerant ferromagnetism in noncentrosymmetric Cr11Ge19

TL;DR

This study reveals complex itinerant ferromagnetism in noncentrosymmetric Cr11Ge19, characterized by unusual magnetic and elastic properties, and supported by experimental and first-principles calculations indicating strong magneto-elastic coupling.

Contribution

It provides new insights into the magnetic behavior and magneto-elastic coupling in Cr11Ge19, highlighting the importance of spin excitations and noncollinear magnetic states.

Findings

Nonlinearity in Arrott plots indicates complex ferromagnetism.

Unusual AC susceptibility behavior suggests complex magnetic dynamics.

Weak heat capacity anomaly near Curie temperature supports itinerant ferromagnetism.

Abstract

The noncentrosymmetric ferromagnet Cr11Ge19 has been investigated by electrical transport, AC and DC magnetization, heat capacity, x-ray diffraction, resonant ultrasound spectroscopy, and first principles electronic structure calculations. Complex itinerant ferromagnetism in this material is indicated by nonlinearity in conventional Arrott plots, unusual behavior of AC susceptibility, and a weak heat capacity anomaly near the Curie temperature (88 K). The inclusion of spin wave excitations was found to be important in modeling the low temperature heat capacity. The temperature dependence of the elastic moduli and lattice constants, including negative thermal expansion along the c axis at low temperatures, indicate strong magneto-elastic coupling in this system. Calculations show strong evidence for itinerant ferromagnetism and suggest a noncollinear ground state may be expected.