Generalized phonon density of states of Mo₃Sb₇ and Mo₃Sb_5.4Te_1.6 from inelastic neutron scattering and lattice dynamical calculations.

Christophe Candolfi (1, 2) , Bertrand Lenoir (1, 2) , Anne Dauscher (1, 2) , Michael Marek Koza (3) , Marc de Boissieu (4) , Małgorzata Sternik (5) , Krzysztof Parlinski (5)

1 IJL - Institut Jean Lamour
2 LPM - Laboratoire de physique des matériaux
3 ILL - Institut Laue-Langevin
4 SIMaP - Science et Ingénierie des Matériaux et Procédés
5 Institute of Physics, Polish Academy of Sciences

The temperature dependence of the generalized phonon density of states (GDOS) of polycrystalline Mo₃Sb₇ and Mo₃Sb_5.4Te_1.6 was studied from 300 K down to 2 K using inelastic neutron scattering. Even though Mo₃Sb₇ undergoes a magnetic as well as a structural phase transition at T* = 53 K, no appreciable change in the recorded spectra has been revealed. The generalized density of states of the nonmagnetic Mo₃Sb_5.4Te_1.6 compound shows similar main characteristics, though substituting Sb by Te leads to a shift of the entire spectrum towards higher energy. The temperature dependence of the GDOS reveals an anomalous softening of phonons with decreasing temperature in Mo₃Sb₇ which cannot be captured by the harmonic approximation while Mo₃Sb_5.4Te_1.6 exhibits a normal behavior. This feature might be related to a strong interplay between magnetic excitations and phonons at the core of the anomalous thermal transport displayed by Mo₃Sb₇. In general, the main characteristics of the experimentally derived GDOS of Mo₃Sb₇ can be reproduced by lattice dynamical calculations.

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Matériaux

Christophe Candolfi, Bertrand Lenoir, Anne Dauscher, Michael Marek Koza, Marc de Boissieu, et al.. Generalized phonon density of states of Mo₃Sb₇ and Mo₃Sb_5.4Te_1.6 from inelastic neutron scattering and lattice dynamical calculations.. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2011, 84 (22), ⟨10.1103/PhysRevB.84.224306⟩. ⟨hal-00664704⟩