Details

Autor(en) / Beteiligte

• Nascimento, M P
• Continentino, M A
• López, A
• de Leo, Ana
• Freitas, D C
• Larrea, J
• Enderlein, Carsten
• Oliveira, J F
• Baggio-Saitovitch, E
• Pospíšil, Jiří
• Fontes, M B

Titel

Magnon excitations and quantum critical behavior of the ferromagnet U4Ru7Ge6

Ist Teil von

• Physical review. B, 2018-11, Vol.98 (17), p.174431

Ort / Verlag

College Park: American Physical Society

Erscheinungsjahr

2018

Quelle

American Physical Society Journals

Beschreibungen/Notizen

• We present an extensive study of the ferromagnetic heavy-fermion compound U4Ru7Ge6. Measurements of electrical resistivity, specific heat, and magnetic properties show that U4Ru7Ge6 orders ferromagnetically at ambient pressure with a Curie temperature TC=6.8±0.3 K. The low-temperature magnetic behavior of this soft ferromagnet is dominated by the excitation of gapless spin-wave modes. Our results on the transport properties of U4Ru7Ge6 under pressures up to 2.49 GPa suggest that U4Ru7Ge6 has a putative ferromagnetic quantum critical point (QCP) at Pc≈1.7±0.02 GPa. In the ordered phase, ferromagnetic magnons scatter the conduction electrons and give rise to a well-defined power law temperature dependence in the resistivity. The coefficient of this term is related to the spin-wave stiffness, and measurements of the very low temperature resistivity show the behavior of this quantity as the ferromagnetic QCP is approached. We find that the spin-wave stiffness decreases with increasing pressure, implying that the transition to the nonmagnetic Fermi liquid state is driven by the softening of the magnons. The observed quantum critical behavior of the magnetic stiffness is consistent with the influence of disorder in our system. At quantum criticality (P=Pc≈1.7±0.02 GPa), the resistivity shows the behavior expected for an itinerant metallic system near a ferromagnetic QCP.