V. Tkáč

Quantum ferromagnet in the proximity of the tricritical point

Echoes of quantum phase transitions at finite temperatures are theoretically and experimentally challenging and unexplored topics. Particularly in metallic quantum ferromagnets the experimental investigations are hampered by an intricate preparation of sufficiently pure samples and the access to the proper coordinates in parameter space. The present study shows that it is possible to tune a specific system at easily accessible conditions to the vicinity of its quantum phase transition. The physics is demonstrated on Ru-doped UCoAl, driven by pressure or substitution to and across the tricritical point and follows the first-order transition line to the theoretically presumed quantum phase transition. These findings open the possibilities for further in-depth studies of classical and quantum critical phenomena at easily reachable conditions.Quantum phase transitions: Tuned in metallic ferromagnetsClean ferromagnetic systems are predicted to exhibit quantum phase transitions (QPTs) rather than critical points. QPTs happen at zero temperature due to quantum fluctuations between the phases, and can be triggered by non-thermal perturbations such as hydrostatic pressure, chemical composition or magnetic fields. Jan Prokleška at Czesh Charles University and colleagues from Czech Republic and Germany demonstrate that it is possible to tune the QPT of the metallic ferromagnet UCo1-xRuxAl by pressure or weak Ru doping. The experimental study of QPTs in metallic ferromagnets is typically hindered by the extreme conditions required to drive the system into the transition, or by the presence of additional phases such as superconductivity. Instead, UCo1-xRuxAl allows to get access to the QPT at easily accessible experimental conditions, opening the possibility of studying in detail quantum critical phenomena.

Coexistence of Antiferromagnetism and Superconductivity in Heavy Fermion Cerium Compound Ce3PdIn11.

We report on magnetization, specific heat and resistivity experiments on single crystals of the novel heavy Fermion compound Ce3PdIn11. At ambient pressure the compound exhibits two successive transitions at T1 = 1.63 K and TN = 1.49 K into incommensurate and commensurate local moment antiferromagnetic states, respectively, before becoming superconducting below Tc = 0.42 K. The large values of dBc2/dT and Bc2 = 2.8 T imply that heavy quasiparticles form the Cooper pairs. Thus, Ce3PdIn11 is the first ambient pressure heavy Fermion superconductor where 4f electrons are simultaneously responsible for magnetic order and superconductivity. PACS numbers: 75.30.Mb,75.30.Kz,74.40.Kb,74.25.DwMany current research efforts in strongly correlated systems focus on the interplay between magnetism and superconductivity. Here we report on coexistence of both cooperative ordered states in recently discovered stoichiometric and fully inversion symmetric heavy fermion compound Ce3PdIn11 at ambient pressure. Thermodynamic and transport measurements reveal two successive magnetic transitions at T1 = 1.67 K and TN = 1.53 K into antiferromagnetic type of ordered states. Below Tc = 0.42 K the compound enters a superconducting state. The large initial slope of dBc2/dT ≈ – 8.6 T/K indicates that heavy quasiparticles form the Cooper pairs. The origin of the two magnetic transitions and the coexistence of magnetism and superconductivity is briefly discussed in the context of the coexistence of the two inequivalent Ce-sublattices in the unit cell of Ce3PdIn11 with different Kondo couplings to the conduction electrons.

Electronic and transport properties of the Mn-doped topological insulator Bi

We present a first-principles study of the electronic, magnetic, and transport properties of the topological insulator Bi

_{2}

_{2}

Te

Te

_{3}

_{3}

: A first-principles study

doped with Mn atoms in substitutional (Mn

Giant reversible rotating cryomagnetocaloric effect inKEr(MoO4)2induced by a crystal-field anisotropy

_{\rm Bi}

Experimental study of magnetic anisotropy in a layered CsNd(MoO4)2

) and interstitial van der Waals gap positions (Mn

Magnetic and structural properties of Mn-doped Bi2Se3 topological insulators

_{\rm i}