Abstract
A quantum critical point (QCP) occurs upon chemical doping of the weak itinerant ferromagnet . Remarkable for a system with no local moments, the QCP is accompanied by non-Fermi liquid behavior, manifested in the logarithmic divergence of the specific heat both in the ferro-and the paramagnetic states, as well as linear temperature dependence of the low-temperature resistivity. With doping, critical scaling is observed close to the QCP, as the critical exponents , , and have weak composition dependence, with nearly twice and almost half of their respective mean-field values. The unusually large paramagnetic moment is nearly composition independent. Evidence for strong spin fluctuations, accompanying the QCP at , may be ascribed to the reduced dimensionality of , associated with the nearly one-dimensional Sc-In chains.
- Received 16 July 2014
- Corrected 16 March 2015
DOI:https://doi.org/10.1103/PhysRevX.5.011026
This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Corrections
16 March 2015
Erratum
Publisher’s Note: Non-Fermi Liquid Behavior Close to a Quantum Critical Point in a Ferromagnetic State without Local Moments [Phys. Rev. X 5, 011026 (2015)]
E. Svanidze, L. Liu, B. Frandsen, B. D. White, T. Besara, T. Goko, T. Medina, T. J. S. Munsie, G. M. Luke, D. Zheng, C. Q. Jin, T. Siegrist, M. B. Maple, Y. J. Uemura, and E. Morosan
Phys. Rev. X 5, 019902 (2015)
Popular Summary
Quantum phase transitions occur at absolute zero temperature and, in contrast to classical phase transitions, are driven by quantum rather than thermal fluctuations. Such transitions have been studied in a large number of magnetic compounds. However, only a small number of itinerant moment (due to delocalized electrons) systems have been investigated, with the majority of quantum critical systems being those with local-moment magnetism. Known examples of quantum phase transitions from a ferromagnetic (compared to antiferromagnetic) ground state are even more rare. We present a ferromagnetic quantum phase transition achieved by doping in an itinerant magnet, , composed of nonmagnetic constituents.
possesses a hexagonal crystalline structure with quasi-one-dimensional Sc-In chains. We find that the highest Curie temperature is achieved for an atomic ratio of . Previous attempts to induce a quantum phase transition in via the application of magnetic fields or pressure were unsuccessful and resulted in an increase in the ordering temperature. We are able to achieve a quantum phase transition in via partial substitution of scandium by nonmagnetic lutetium ions. The resulting quantum phase transition is accompanied by non-Fermi-liquid behavior, a departure from the expected Fermi-liquid behavior in normal (noninteracting) metals. Moreover, the critical scaling of the magnetization yields non-mean-field values of the critical exponents. The non-Fermi-liquid and non-mean-field behavior are both similar to what has been observed in the heavy fermion ferromagnet , which is two dimensional. Lutetium-doped exhibits low-temperature resistivity that is linear with temperature.
Our findings provide a connection between two seemingly different ferromagnetic systems, paving the way toward a unified picture of quantum criticality and non-Fermi-liquid behavior in itinerant magnets.
