Scientific Highlights & News
Strain engineering of the charge and spin-orbital interactions in Sr2IrO4
Understanding the relationship between entangled degrees of freedom (DOF) is a central problem in correlated materials and the possibility to influence their balance is promising toward realizing novel functionalities. In Sr2IrO4, the interaction between spin–orbit coupling and electron correlations induces an exotic ground state with magnetotransport properties promising for antiferromagnetic spintronics applications.
Electron–phonon-driven three-dimensional metallicity in an insulating cuprate
Elucidating the role of different degrees of freedom in a phase transition is crucial in the comprehension of complex materi- als. A phase transformation that attracts significant interest is the insulator-to-metal transition of Mott insulators, in which the electrons are thought to play the dominant role. Here, we use ultrafast laser spectroscopy and theoretical calculations ....
Magnetism and anomalous transport in the Weyl semimetal PrAlGe: possible route to axial gauge fields
In magnetic Weyl semimetals, where magnetism breaks time-reversal symmetry, large magnetically sensitive anomalous transport responses are anticipated that could be useful for topological spintronics. The identification of new magnetic Weyl semimetals is therefore in high demand, particularly since in these systems Weyl node configurations may be easily modified using magnetic fields. Here we explore experimentally the magnetic semimetal PrAlGe, and unveil a direct correspondence between easy-axis Pr ferromagnetism and anomalous Hall and Nernst effects.
Topological Magnetic Phase in the Candidate Weyl Semimetal CeAlGe
We report the discovery of topological magnetism in the candidate magnetic Weyl semimetal CeAlGe. Using neutron scattering we find this system to host several incommensurate, square-coordinated multi-k⃗ magnetic phases below TN. The topological properties of a phase stable at intermediate magnetic fields parallel to the c axis are suggested by observation of a topological Hall effect.
Nodeless superconductivity and its evolution with pressure in the layered dirac semimetal 2M-WS2
Recently, the transition metal dichalcogenide (TMD) system 2M-WS2 has been identified as a Dirac semimetal exhibiting both superconductivity with the highest Tc ~ 8.5 K among all the TMD materials and topological surface states. Here we report on muon spin rotation (μSR) and density functional theory studies of microscopic SC properties and the electronic structure in 2M-WS2 at ambient and under hydrostatic pressures (pmax = 1.9 GPa).
PhD Defence Fei Li
On 31.05.2019, Fei Li passed successfully his PhD defence at the ETH Materials Department. The title of his thesis is "Crystal and Magnetic Structure of R1/3Sr2/3FeO3 (R = La,Pr,Nd)”
DGKK Award for young researchers 2019 for Pascal Puphal
Dr Pascal Puphal (currently a Postdoc at PSI, LMX, Solid State Chemistry Group) has recently been awarded with the DGKK young researcher price from the German Crystal Growth Community on his Ph.D. work performed in the group of Cornelius Krellner at the Geothe University Frankfurt am Main on the topic "Tuning two dimensional Cu-based quantum spin systems". The work covers the stabilization and proof of a 2D dimer structure by Sr substitution in Han Purple and the research of novel kagome materials of the prominent quantum spin liquid candidate herbertsmithite by the hydrothermal route.
Bulk single-crystal growth of the theoretically predicted magnetic Weyl semimetals RAlGe (R = Pr, Ce)
We explore two methods for single-crystal growth of the theoretically proposed magnetic Weyl semimetals RAlGe (R = Pr, Ce), which prove that a floating-zone technique, being both crucible- and flux-free, is crucial to obtain perfectly stoichiometric RAlGe crystals. In contrast, the crystals grown by a flux-growth technique tend to be Al-rich. We further present both structural and elemental analyses, along with bulk magnetization and electrical resistivity data on the crystals prepared by the floating-zone technique. Both systems with the intended 1:1:1 stoichiometry crystallize in the anticipated polar I41md (No. 109) space group, although neither displays the theoretically expected ferromagnetic ground state.
Spin triplet ground-state in the copper hexamer compounds A2Cu3O(SO4)3 (A = Na, K)
The compounds A2Cu3O(SO4)3(A=Na,K) are characterized by copper hexamers which are weakly coupled along the b axis to realize one-dimensional antiferromagnetic chains below TN≈3K, whereas the interchain interactions along the a and c axes are negligible. We investigated the energy-level splittings of the copper hexamers by inelastic neutron scattering below and above TN.