Heavy Fermion; charge density wave; unconventional superconductivity; Magnetism; spin density wave; neutron scattering; Quantum critical point; SANS
Mazzone Daniel et al. (2017), Spin Resonance and Magnetic Order in an Unconventional Superconductor, in
Phys. Rev. Lett, 199(18), 187002-1-187002-5.
Mazzone Daniel et al. (2017), Field induced magnetic instability within a superconducting condensate, in
SCIENCE ADVANCES, (5 ), e1602055.
Biswas Pabitra et al. (2016), Fully gapped superconductivity in the topological superconductor beta-PdBi2, in
PHYSICAL REVIEW B, 93(22), 220504.
Mazzone Daniel et al. (2015), Crystal structure and phonon softening in Ca3Ir4Sn13, in
PHYSICAL REVIEW B, 92(2), 024101.
Mazzone Daniel et al. (2015), Distinct vortex-glass phases in Yb3Rh4Sn13 at high and low magnetic fields, in
OURNAL OF PHYSICS-CONDENSED MATTER , 27(24), 245701.
Fornassini M.L. et al. (2014), New structures formed by R3Au4Sn3, R5Au8Sn5 and R3Au6Sn5 compounds (R = rare earths), in
Intermetallics, 63, 169.
Mazzone Daniel et al. (2014), Small angle neutron scattering study oft he mixed state of Yb3Rh4Sn13, in
Phys. Rev. B, 90(2), 02507.
Mazzone Daniel et al., Distinct domain switching in Nd$_{0.05}$Ce$_{0.95}$CoIn$_5$ at low and high fields, in
Scientific Reports.
We request funding for two Ph.D. students to experimentally study superconductivity in unconventional metals and its interplay with magnetism. The superconducting (SC) systems of our interest are materials displaying heavy-fermion phenomena and/or Fermi surface instabilities, such as charge density wave (CDW) and spin-density wave (SDW). The physical properties of these systems are governed by strong electron-electron correlations, for which there is no microscopic description. Unconventional superconductivity develops from a paramagnetic heavy-fermion state, but it may also develop from SDW or CDW states. In other cases SDW states appear inside the superconducting state. In spite of intense research efforts, the interrelations between the SC, SDW and CDW states remain unclear. The properties of the ground state of real materials may be altered by adjusting a physical parameter (“tuning”). The parameter, x, may be the external magnetic field, pressure or chemical substitution. In some cases, tuning induces a phase transition at T = 0 K, a quantum critical point QCP (at a critical value xc). At, and near, xc the physical properties of the system are dominated by quantum fluctuation resulting in a new state of matter. For systems close to a magnetic instability one distinguishes two types of QCPs depending on the evolution of the Fermi surface near xc. (i) The Fermi surface undergoes only minor changes, SDW type. (ii) The Fermi surface undergoes large changes due to “Kondo- screening destruction”. By analogy, a system close to a CDW instability may result in a QCP, where quantum fluctuations are associated to charge fluctuations near the onset of the CDW instability (CDW-QCP). We plan to investigate materials, where SDW and or CDW instabilities are likely to occur and are superconducting at low temperatures. The aim of our studies is to map out the features that may be attributed to charge and/or spin fluctuations in a variety of different superconducting materials. Materials of interest will be synthesized in the Laboratory of Prof. K. Conder at PSI and of prof. A. Bianchi at the university of Montreal. Characterization by thermal and transport properties will be performed at PSI. High quality single crystalline samples will be selected for further neutron scattering and µSR measurements.