Research Highlights

Non-collinear Heusler antiferromagnet Pt2MnGa

Scientists from the Max Planck Institute for Chemical Physics of Solids, Dresden, the ILL in Grenoble, and the HLD have studied the new room-temperature tetragonal non-collinear Heusler AFM Pt2MnGa. read more

Broadband spectroscopy at extreme magnetic fields: First results

Magnetic fields exceeding 100 T can be obtained only by semi-destructive methods. In one approach, the magnetic field is generated by a single-turn coil, which explodes during the pulse leaving the cryostat where the sample is mounted intact. Very high magnetic fields can be generated, up to 350 T, at the expense of the pulse duration of approximately 5 μs. In spite of this experimentally challenging environment, sensitive optical measurements can be performed. read more

Magneto-optics of monolayer tungsten disulfide

Single-layer transition-metal dichalcogenides, such as MoS2, MoSe2, WS2, WSe2, are two-dimensional semiconductors with a honeycomb lattice. Their band structures show a pair of inequivalent valleys (local extrema) at the +K and -K points of the Brillouin zone. read more

Electrons in flat bands

Layered materials can realize different stackings of their individual planes, different polytypes, to compose three-dimensional structures. ABA-stacked graphite is the most stable form of graphite at ambient conditions and the study of thin layers of this material have revealed many interesting phenomena related to the change of the nature of quasiparticles when adding layers one by one. read more

Magnetic-field suppression of thermoelectricity in a metallic frustrated magnet

In a publication in Physical Review Letters, EMFL scientists together with colleagues from POSTECH in Korea, have demonstrated that the TE in a metallic frustrated magnet can be completely suppressed by applying high magnetic fields of 30 T. read more

Disorder-induced stabilization of the quantum Hall ferromagnet

The quantum Hall ferromagnet (QHF) is a fascinating ground state of two-dimensional (2D) electrons in a magnetic field where exchange interactions can establish a long-range ferromagnetic order. The current work gives an explanation for the QHF's spin polarization fragility by showing that an optimal amount of disorder actually “protects” the QHF against depolarization. read more

Magnetoelectric effect and phase transitions in CuO in external magnetic fields

By synergistic use of a number of experimental techniques combined with high magnetic fields – single-crystal neutron diffraction, electric polarization, ultrasound, magnetization, capacitance and magnetostriction measurements at the European facilities (HLD-EMFL at HZDR in Dresden and ILL in Grenoble) – researchers from Dresden and Barcelona, in collaboration with colleagues from Grenoble and Moscow, were able to shed light on the puzzling magnetoelectric nature of CuO. read more

Nanoscale study of polymer dynamics

The thermal motion of polymer chains in a crowded environment is anisotropic and highly confined. Whereas the dynamics are theoretically and experimentally quite well understood, typically only indirect and bulk information on polymer dynamics was obtained from studies such as light scattering, NMR and rheology. read more


Electrical Switch to the Resonant Magneto-Phonon Effect in Graphene

Atomic vibrations of a graphene crystal, phonons, can hybridize with electronic excitations. This hybridization is particularly pronounced when a magnetic field is applied perpendicular to the plane of the two dimensional crystal with an intensity tuned so that the energy of electronic excitations coincides with that of the phonon. This effect is called the magneto-phonon effect and manifests itself through pronounced variations of the phonon energy each time an electronic excitation is tuned to the phonon energy. It can be observed through light scattering experiments (Raman scattering) performed at low temperatures and in high magnetic fields. read more

Pnictides go critical

The two most important families of so-called high-temperature superconductors, those based on copper (the cuprates) and those based on iron (the pnictides), turn out to have a fundamental difference. In the work published in Nature Physics on January 19, 2014, high magnetic fields were used to strip away the superconductivity of pnictides. This reveals more about the nature of the metallic (or resistive) state from which the superconductivity (the zero-resistive state) emerges. The EMFL researchers compared the results with earlier research on cuprates, which was published in Science in 2009. read more

Researchers show giant diamagnetism of gold nanorods 

Like most materials, bulk gold is diamagnetic, exhibiting only a weak response to an external magnetic field. EMFL Researchers from the HFML Nijmegen, in collaboration with scientists of Leiden University, The Netherlands, have now found drastically enhanced diamagnetism in gold nanoparticles. Using a new, very sensitive, magneto-optical technique, the researchers were able to determine the magnetic response of gold nanorods suspended in water, to find a diamagnetic signal that is 14 times larger than that of bulk gold. This effect can be attributed to the behaviour of the free electrons within the small nanoparticles and represents an alternative source of magnetism. read more