From valence fluctuations to long-range magnetic order in EuPd${}_2$(Si${}_{1-x}$Ge${}_x$)${}_2$ single crystals

Abstract

EuPd${}_2$Si${}_2$ is a valence-fluctuating system undergoing a temperature-induced valence crossover at $T_V^{\prime }\approx 160$K. We present the successful single crystal growth using the Czochralski method for the substitution series EuPd${}_2$(Si${}_{1-x}$Ge${}_x$)${}_2$, with substitution levels $x\le 0.15$. A careful determination of the germanium content revealed that only half of the nominal concentration is build into the crystal structure. From thermodynamic measurements it is established that $T_V^{\prime }$ is strongly suppressed for small substitution levels and antiferromagnetic order from stable divalent europium emerges for $x\gtrsim 0.10$. The valence transition is accompanied by a pronounced change of the lattice parameter $a$ of order 1.8%. In the antiferromagnetically ordered state below $T_N=47$ K, we find sizeable magnetic anisotropy with an easy plane perpendicular to the crystallographic c direction. An entropy analysis revealed that no valence fluctuations are present for the magnetically ordered materials. Combining the obtained thermodynamic and structural data, we construct a concentration-temperature phase diagram demonstrating a rather abrupt change from a valence-fluctuating to a magnetically-ordered state in EuPd${}_2$(Si${}_{1-x}$Ge${}_x$)${}_2$.

References in corpus (9)

• Pressure-induced volume-collapsed tetragonal phase of CaFe2As2 as seen via neutron scattering
• Unified Molecular Field Theory for Collinear and Noncollinear Heisenberg Antiferromagnets
• Complex and strongly anisotropic magnetism in the pure spin system EuRh2Si2
• Quantum Criticality of Valence Transition for the Unique Electronic State of Antiferromagnetic Compound EuCu2Ge2
• Influence of the Pd-Si ratio on the valence transition in EuPd${}_2$Si${}_2$ single crystals
• Observation of Two Collapsed Phases in CaRbFe4As4
• Microscopic analysis of the valence transition in tetragonal EuPd${}_2$Si${}_2$
• Strong electron-phonon coupling and enhanced phonon Grüneisen parameters in valence-fluctuating metal EuPd${}_2$Si${}_2$
• Clamping effect on temperature-induced valence transition in epitaxial EuPd${}_2$Si${}_2$ thin films grown on MgO(001)

Cited by in corpus (1)

• Pressure study on the interplay between magnetic order and valence-change crossover in EuPd${}_2$(Si${}_{1-x}$Ge${}_x$)${}_2$