Anomalous pressure dependence of the bulk modulus and Yb valence in cubic YbPd

Abstract

We investigate the Yb valence instabilities in the strongly correlated YbPd compound using resonant X-ray emission spectroscopy as a function of pressure across the charge-order (CO) transition. At a low temperature (T = 30 K) in the CO phase, the Yb $4f$ valence remains nearly constant up to a pressure P${}_L$ = 1.5 $\pm 0.2$ GPa, and then increases gradually at higher pressures. In contrast, at room temperature in the normal phase, an anomalous decrease of the Yb $4f$ valence is observed, without any accompanying structural phase transition. This behavior is corroborated by a systematic pressure-dependent decrease of the unit-cell volume. Based on a Birch-Murnaghan analysis, the compressibility indicates hardening of the lattice with applied pressure up to a distinct kink seen at P${}_K$ = 1.6 $\pm 0.2$ GPa. In contrast, for P $>$ P${}_K$, the Yb $4f$ valence saturates and the compressibility reveals a counterintuitive pressure-induced softening. The results show a minimum in the compressibility of YbPd (with $f^0$-$f^1$ hole-type mixed-valence), reminiscent of the maximum in compressibility seen in the $\gamma$-$\alpha$ first-order isostructural phase transition in cerium (with $f^0$-$f^1$ electron-type mixed-valence).

arXiv comment6 pages, 4 figures

References in corpus (16)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Quantum Criticality in Heavy Fermion Metals
• Negative Linear Compressibility
• The role of the lattice in the $\gamma \to \alpha$ phase transition of Ce: a high pressure neutron and x-ray diffraction study
• Pressure-induced softening as a common feature of framework structures that have negative thermal expansion
• Common origin of exotic properties in ceramic and hybrid negative thermal expansion materials
• Pressure-Induced Valence Crossover and Novel Metamagnetic Behavior near the Antiferromagnetic Quantum Phase Transition of YbNi${}_3$Ga${}_9$
• Colossal pressure-induced softening in scandium fluoride
• Temperature-dependent pressure-induced softening in Zn(CN)${}_2$
• Valence Instability of YbCu${}_2$Si${}_2$ through its quantum critical point
• Similar temperature scale for valence changes in Kondo lattices with different Kondo temperatures
• Charge ordering in the intermediate valence magnet YbPd
• Interplay between Charge and Magnetic Ordering in YbPd
• Intermediate valence in single crystalline Yb${}_2$Si${}_2$Al
• Variation of Pressure-Induced Valence Transition with Approximation Degree in Yb-Based Quasicrystalline Approximants
• Intermediate Valence State in $\mathrm{Yb}{\mathrm{B}}_4$ Revealed by Resonant X-ray Emission Spectroscopy