Quantum phase transitions and multicriticality in Ta(Fe1-xVx)2

• Published in: arXiv.org 2016-06
• Main Authors: Brando, Manuel, Kerkau, Alexander, Todorova, Adriana, Yamada, Yoshihiro, Khuntia, Panchanan, Foerster, Tobias, Burkhardt, Ulrich, Baenitz, Michael, Kreiner, Guido
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Critical point; Crystal lattices; Crystal structure; Domes; Fermi liquids; Ferromagnetism; Heat exchange; Laves phase; Phase diagrams; Phase transitions; Spin density waves; Structural analysis; Temperature dependence; Thermodynamic properties; Transition temperature; Vanadium; Variations
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1606.09416

We present a comprehensive study of synthesis, structure analysis, transport and thermodynamic properties of the C14 Laves phase Ta(Fe1-xVx)2. Our measurements confirm the appearance of spin-density wave (SDW) order within a dome-like region of the x - T phase diagram with vanadium content 0.02 < x < 0.3. Our results indicate that on approaching TaFe2 from the vanadium-rich side, ferromagnetic (FM) correlations increase faster than the antiferromagnetic (AFM) ones. This results in an exchange-enhanced susceptibility and in the suppression of the SDW transition temperature for x < 0.13 forming the dome-like shape of the phase diagram. This effect is strictly related to a significant lattice distortion of the crystal structure manifested in the c/a ratio. At x = 0.02 both FM and AFM energy scales have similar strength and the system remains paramagnetic down to 2 K with an extremely large Stoner enhancement factor of about 400. Here, spin fluctuations dominate the temperature dependence of the resistivity \rho ~ T ^ 3/2 and of the specific heat C/T ~ - log(T) which deviate from their conventional Fermi liquid forms, inferring the presence of a quantum critical point of dual nature.