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Title: Evolution of critical pressure with increasing Fe substitution in the heavy-fermion system URu 2 - x Fe x Si 2

Measurements of electrical resistivity, ρ(T ), were performed under quasihydrostatic pressure up to P ~ 2.2 GPa to determine the pressure dependence of the so-called hidden order (HO) and large-moment antiferromagnetic (LMAFM) phases for the URu 2-xFexSi2 system with x = 0.025, 0.05, 0.10, 0.15, and 0.20. As the Fe concentration (x) is increased, we observed that a smaller amount of external pressure, P c, is required to induce the HO → LMAFM phase transition. A critical pressure of P c ~ 1.2 GPa at x = 0.025 reduces to P c ~ 0 at x = 0.15, suggesting the URu 2-xFe xSi 2 system is fully expressed in the LMAFM phase for x ≥ x* c = 0.15, where x * c denotes the ambient pressure critical concentration of Fe. Furthermore, when using a bulk modulus calculation to convert x to chemical pressure, P ch(x), we consistently found that the induced HO → LMAFM phase transition occurred at various combinations of x c and P c such that P ch(x c) + P c ≈ 1.5 GPa, where xc denotes those critical concentrations of Fe that induce the HO→LMAFM phase transition for the URu 2-xFe xSi 2 compoundsmore » under pressure. We performed exponential fits of ρ(T ) in the HO and LMAFM phases in order to determine the pressure dependence of the energy gap, , that opens over part of the Fermi surface in the transition from the paramagnetic (PM) phase to the HO/LMAFM phase at the transition temperature, T 0. Finally, this change in the pressure variation of Δ(P) at the HO→LMAFM phase transition is consistent with the values of P c determined from the T 0(P) phase lines at the PM→HO/LMAFM transition.« less
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  1. Univ. of California, San Diego, CA (United States)
Publication Date:
Grant/Contract Number:
NA0002909; FG02-04ER46105
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 8; Journal ID: ISSN 2469-9950
American Physical Society (APS)
Research Org:
Univ. of California, San Diego, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1310833; OSTI ID: 1361432