Magnetocalorics of singlet ground state induced moment magnets

Abstract

In f-electron materials like Pr or U compounds with non-Kramers states of the f-shell the ground state may be a nonmagnetic singlet due to the action of the crystalline electric field. Nevertheless these compounds can order magnetically. They develop a ground state moment and long range order due to the spontaneous admixture of the excited state into the ground state caused by inter-site exchange. This mechanism can establish magnetic order if a control parameter exceeds a critical value defining the quantum critical point between disordered and magnetic phase. Here we investigate the magnetocaloric properties of such quantum magnets where the entropy release at low temperature is due to a competition between thermal depopulation and spontaneous order effects. We determine field and temperature dependence of specific heat for ferro- and antiferromagnetic order and also calculate the adiabatic magneto- and barocaloric cooling rates. As a model application we discuss the magnetic specific heat of the new induced ferromagnet PrIr3. Furthermore we analyze the excitation spectrum of the singlet induced moment magnets in an external field with particular emphasis on field and temperature dependence of the critical soft mode. We find that the latter is fragile and exists only at specific points in the phase diagram.

15 pages,11 figures; published version

References in corpus (13)

• Frustrated two dimensional quantum magnets
• Direct bulk sensitive probe of 5f symmetry in URu2Si2
• Theory of induced quadrupolar order in tetragonal YbRu_{2}Ge_{2}
• Magnetic order and single-ion anisotropy in Tb${}_3$Ga${}_5$O${}_{12}$
• Exchange renormalized crystal field excitation in a quantum Ising magnet KTmSe${}_2$
• Singlet magnetism in intermetallic UGa${}_2$ unveiled by inelastic x-ray scattering
• Induced quantum magnetism in CEF singlet ground state models: Thermodynamics and excitations
• Induced order and collective excitations in three-singlet quantum magnets
• Topological paramagnetic excitons of localized f electrons on the honeycomb lattice
• Fe substitution in URu${}_2$Si${}_2$: singlet magnetism in an extended Doniach phase diagram
• Interplay of itinerant electrons and Ising moments in a hybrid honeycomb quantum magnet TmNi${}_3$Al${}_9$
• Ferromagnetism and structural phase transition in rhombohedral PrIr3
• Realization of giant elastocaloric cooling at cryogenic temperatures in TmVO${}_4$ via a strain load/unload technique

Cited by in corpus (1)

• Hyperfine coupling in singlet ground state magnets