Quantum Critical Scaling in the Disordered Itinerant Ferromagnet ${\mathrm{UCo}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x}\mathrm{Ge}$

Quantum Critical Scaling in the Disordered Itinerant Ferromagnet ${UCo}_{1 - x} {Fe}_{x} Ge$

K. Huang, S. Eley, P. F. S. Rosa, L. Civale, E. D. Bauer, R. E. Baumbach, M. B. Maple, and M. Janoschek

Phys. Rev. Lett. 117, 237202 – Published 30 November 2016

Abstract

The Belitz-Kirkpatrick-Vojta (BKV) theory shows in excellent agreement with experiment that ferromagnetic quantum phase transitions (QPTs) in clean metals are generally first order due to the coupling of the magnetization to electronic soft modes, in contrast to the classical analogue that is an archetypical second-order phase transition. For disordered metals the BKV theory predicts that the second-order nature of the QPT is restored because the electronic soft modes change their nature from ballistic to diffusive. Our low-temperature magnetization study identifies the ferromagnetic QPT in the disordered metal ${UCo}_{1 - x} {Fe}_{x} Ge$ as the first clear example that exhibits the associated critical exponents predicted by the BKV theory.

Received 2 August 2016

DOI:https://doi.org/10.1103/PhysRevLett.117.237202

Physics Subject Headings (PhySH)

Magnetic phase transitions Quantum criticality

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

K. Huang^1,2, S. Eley¹, P. F. S. Rosa¹, L. Civale¹, E. D. Bauer¹, R. E. Baumbach^1,*, M. B. Maple², and M. Janoschek^1,†

¹Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
²Department of Physics, University of California, San Diego, La Jolla, California 92093, USA

^*Present address: Condensed Matter Group, National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
^†Corresponding author. mjanoschek@lanl.gov