Valence and magnetic ordering in intermediate valence compounds : TmSe versus SmB6

Abstract

The intermediate valent systems TmSe and SmB6 have been investigated up to 16 and 18 GPa by ac microcalorimetry with a pressure (p) tuning realized in situ at low temperature. For TmSe, the transition from an antiferromagnetic insulator for p<3 GPa to an antiferromagnetic metal at higher pressure has been confirmed. A drastic change in the p variation of the Neel temperature (Tn) is observed at 3 GPa. In the metallic phase (p>3 GPa), Tn is found to increase linearly with p. A similar linear p increase of Tn is observed for the quasitrivalent compound TmS which is at ambiant pressure equivalent to TmSe at p=7 GPa. In the case of SmB6 long range magnetism has been detected above p=8 GPa, i.e. at a pressure slightly higher than the pressure of the insulator to metal transition. However a homogeneous magnetic phase occurs only above 10 GPa. The magnetic and electronic properties are related to the renormalization of the 4f wavefunction either to the divalent or the trivalent configurations. As observed in SmS, long range magnetism in SmB6 occurs already far below the pressure where a trivalent Sm3+ state will be reached. It seems possible, to describe roughly the physical properties of the intermediate valence equilibrium by assuming formulas for the Kondo lattice temperature depending on the valence configuration. Comparison is also made with the appearance of long range magnetism in cerium and ytterbium heavy fermion compounds.

22 pages including figures

References in corpus (3)

• Electron self-trapping in intermediate-valent SmB6
• Collective magnetic excitations in mixed-valence Sm0.83Y0.17S
• Kondo engineering : from single Kondo impurity to the Kondo lattice

Cited by in corpus (15)

• Unconventional Fermi surface in an insulating state
• Unconventional Superconductivity in UTe2
• Multiple Superconducting Phases and Unusual Enhancement of the Upper Critical Field in UTe2
• Magnetic Properties under Pressure in Novel Spin-Triplet Superconductor UTe2
• Pressure-resistant intermediate valence in Kondo insulator SmB6
• Interplay of magnetism, Fermi surface reconstructions, and hidden-order in the heavy-fermion material URu${}_2$Si${}_2$
• Magnetic field-tuned quantum criticality in a Kondo insulator
• Collapse of antiferromagnetism in CeRh2Si2 : volume versus entropy
• Novel Kondo-like behavior near magnetic instability in SmB${}_6$ : temperature and pressure dependences of Sm valence
• Irreversible proliferation of magnetic moments at cleaved surfaces of the topological Kondo insulator SmB6
• ${\mathcal{Z}}_2$ classification for a novel antiferromagnetic topological insulating phase in three-dimensional topological Kondo insulator
• Hall coefficient diagnostics of surface state in pressurized SmB6
• Correlation Induced Magnetic Topological Phases in Mixed-Valence Compound SmB6
• Valence transition in topological Kondo insulator
• Anomalous 4$f$ fine structure in TmSe${}_{1-x}$Te${}_x$ across the metal-insulator transition