Isoelectronic perturbations to f- d-electron hybridization and the enhancement of hidden order in URu2Si2

Christian T Wolowiec; Noravee Kanchanavatee; Kevin Huang; Sheng Ran; Alexander J Breindel; Naveen Pouse; Kalyan Sasmal; Ryan E Baumbach; Greta Chappell; Peter S Riseborough; M Brian Maple

doi:10.1073/pnas.2026591118

Isoelectronic perturbations to f- d-electron hybridization and the enhancement of hidden order in URu₂Si₂

Proc Natl Acad Sci U S A. 2021 May 18;118(20):e2026591118. doi: 10.1073/pnas.2026591118.

Authors

Christian T Wolowiec^{1

2}, Noravee Kanchanavatee^{1

2}, Kevin Huang^{1

2}, Sheng Ran^{1

2}, Alexander J Breindel^{1

2}, Naveen Pouse^{1

2}, Kalyan Sasmal^{1

2}, Ryan E Baumbach^{3

4}, Greta Chappell^{3

4}, Peter S Riseborough⁵, M Brian Maple^{6

2}

Affiliations

¹ Department of Physics, University of California San Diego, La Jolla, CA 92093.
² Center for Advanced Nanoscience, University of California San Diego, La Jolla, CA 92093.
³ National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310.
⁴ Department of Physics, Florida State University, Tallahassee, FL 32306.
⁵ Physics Department, Temple University, Philadelphia, PA 19122.
⁶ Department of Physics, University of California San Diego, La Jolla, CA 92093; mbmaple@ucsd.edu.

Abstract

Electrical resistivity measurements were performed on single crystals of URu_2-x Os _x Si₂ up to x = 0.28 under hydrostatic pressure up to P = 2 GPa. As the Os concentration, x, is increased, 1) the lattice expands, creating an effective negative chemical pressure P_ch(x); 2) the hidden-order (HO) phase is enhanced and the system is driven toward a large-moment antiferromagnetic (LMAFM) phase; and 3) less external pressure P_c is required to induce the HO→LMAFM phase transition. We compare the behavior of the T(x, P) phase boundary reported here for the URu_2-x Os _x Si₂ system with previous reports of enhanced HO in URu₂Si₂ upon tuning with P or similarly in URu_2-x Fe _x Si₂ upon tuning with positive P_ch(x). It is noteworthy that pressure, Fe substitution, and Os substitution are the only known perturbations that enhance the HO phase and induce the first-order transition to the LMAFM phase in URu₂Si₂ We present a scenario in which the application of pressure or the isoelectronic substitution of Fe and Os ions for Ru results in an increase in the hybridization of the U-5f-electron and transition metal d-electron states which leads to electronic instability in the paramagnetic phase and the concurrent formation of HO (and LMAFM) in URu₂Si₂ Calculations in the tight-binding approximation are included to determine the strength of hybridization between the U-5f-electron states and the d-electron states of Ru and its isoelectronic Fe and Os substituents in URu₂Si₂.

Keywords: URu2Si2; hidden order; hybridization; isoelectronic; pressure.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.