Browsing by Author "Brando, Manuel"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Anisotropy-driven quantum criticality in an intermediate valence system
    (Springer Nature, 2022) Grbić, Mihael S.; O’Farrell, Eoin C. T.; Matsumoto, Yosuke; Kuga, Kentaro; Brando, Manuel; Küchler, Robert; Nevidomskyy, Andriy H.; Yoshida, Makoto; Sakakibara, Toshiro; Kono, Yohei; Shimura, Yasuyuki; Sutherland, Michael L.; Takigawa, Masashi; Nakatsuji, Satoru
    Intermetallic compounds containing f-electron elements have been prototypical materials for investigating strong electron correlations and quantum criticality (QC). Their heavy fermion ground state evoked by the magnetic f-electrons is susceptible to the onset of quantum phases, such as magnetism or superconductivity, due to the enhanced effective mass (m*) and a corresponding decrease of the Fermi temperature. However, the presence of f-electron valence fluctuations to a non-magnetic state is regarded an anathema to QC, as it usually generates a paramagnetic Fermi-liquid state with quasiparticles of moderate m*. Such systems are typically isotropic, with a characteristic energy scale T0 of the order of hundreds of kelvins that require large magnetic fields or pressures to promote a valence or magnetic instability. Here we show the discovery of a quantum critical behaviour and a Lifshitz transition under low magnetic field in an intermediate valence compound α-YbAlB4. The QC origin is attributed to the anisotropic hybridization between the conduction and localized f-electrons. These findings suggest a new route to bypass the large valence energy scale in developing the QC.
  • Thumbnail Image
    Item
    CeIr3Ge7: A local moment antiferromagnetic metal with extremely low ordering temperature
    (American Physical Society, 2018) Rai, Binod K.; Banda, Jacintha; Stavinoha, Macy; Borth, R.; Jang, D.-J.; Benavides, Katherine A.; Sokolov, D. A.; Chan, Julia Y.; Nicklas, M.; Brando, Manuel; Huang, C.-L.; Morosan, E.
    CeIr3Ge7 is an antiferromagnetic metal with a remarkably low ordering temperature TN=0.63K, while most Ce-based magnets order between 2 and 15 K. Thermodynamic and transport properties as a function of magnetic field or pressure do not show signatures of Kondo correlations, interaction competition, or frustration, as had been observed in a few antiferromagnets with comparably low or lower TN. The averaged Weiss temperature measured below 10 K is comparable to TN, suggesting that the Ruderman-Kittel-Kasuya-Yosida exchange coupling is very weak in this material. The unusually low TN in CeIr3Ge7 can therefore be attributed to the large Ce-Ce bond length of about 5.7 Å, which is about 1.5 Å larger than in the most Ce-based intermetallic systems.
  • Thumbnail Image
    Item
    Type-I superconductivity in YbSb2 single crystals
    (American Physical Society, 2012) Zhao, Liang L.; Lausberg, Stefan; Kim, H.; Tanatar, M.A.; Brando, Manuel; Prozorov, R.; Morosan, E.
    We present evidence of type-I superconductivity in YbSb2 single crystals from dc and ac magnetization, heat capacity, and resistivity measurements. The critical temperature and critical field are determined to be Tc ≈ 1.3 K and Hc ≈ 55 Oe. A small Ginzburg-Landau parameter κ = 0.05, together with typical magnetization isotherms of type-I superconductors, small critical field values, a strong differential paramagnetic effect signal, and a fieldinduced change from second- to first-order phase transition, confirms the type-I nature of the superconductivity in YbSb2. A possible second superconducting state is observed in the radio-frequency susceptibility measurements, with T (2) c ≈ 0.41 K and H(2) c ≈ 430 Oe.