Groups / Labs
Materials synthesis laboratory
Materials synthesis laboratory hosts a molecular beam epitaxy (MBE) system (Veeco Gen II) dedicated to As-based III-V semiconductors and semiconductor heterostructures, ferromagnetic semiconductors, combined non-magnetic/ferromagnetic structures, and antiferromagnetic CuMnAs. The system is extended by an ultra high vacuum (UHV) evaporation unit with four electron beam sources. This allows for combining the MBE grown structures with thin layers of metallic and dielectric materials, retaining the atomically smooth interfaces. In 2019, two new MBE chambers (Eberl MBE-Komponenten) will be added to the laboratory for the growth of antiferromagnetic materials.
Nano-fabrication clean room laboratory
Nano-fabrication clean room laboratory hosts an e-beam lithography unit (Raith e-Line) and a complete chain of sample processing technologies. This includes plasma etching system (Oxford Instruments Plasmalab 100, Diener Electronics FEMTO), set of flow boxes and boxes for chemical etching, metal evaporation and sputtering systems (Angstrom Covap, Leybold-Heraeus) and a UV light mask aligner (Elektromat JUB2) for auxiliary optical lithography.
Magneto-transport laboratory comprises a set of helium cryostats (Oxford Instruments and Advanced Research Systems) for magneto-transport measurements in temperature range 0.2 - 800 K and magnetic fields up to 11 T. The laboratory is equipped for wide range of electrical measurements including DC measurements (e.g. Agilent B1500 Semiconductor Device Analyzer), AC lock-in measurements, high frequency measurements (R&S 50 GHz Vector Network Analyzer), and short pulse experiments with pulse lengths down to sub-nanosecond range. The transport laboratory is complemented with a SQUID magnetometry system (Quantum Design) for temperature range 2 – 800 K and magnetic fields up to 7 T.
The theory group employs a wide range of techniques to study properties of solid materials, in close collaboration with experimentalists in our department. A primary focus of the group is on the calculation and theoretical understanding of transport phenomena, mainly in relation to spintronics and generally transport in magnetic materials. We study effects such as the spin-orbit torque, the spin or the anomalous Hall effects or the anisotropic magnetoresistance. In addition, we utilize various ab-initio and tight-binding techniques for the description of the ground state electronic and magnetic structure. In the past, the group concentrated primarily on ferromagnetic semiconductors. In recent years the focus has shifted more towards magnetic, especially antiferromagnetic, metals.
Joint Opto-Spintronics laboratory
Joint Opto-Spintronics laboratory is formed by femtosecond Ti:sapphire laser (Mai Tai HP, Spectra Physics) supplemented by optical parametric oscillator (Inspire HF, Spectra Physics) that provide a gap free tuneability of femtosecond laser pulses from 350 nm (3.5 eV) to 2.2 µm (0.56 eV) at a repetition rate of 82 MHz; the repetition rate can be reduced down to single pulse using a pulse picker. The sample can be placed in a closed-cycle helium cryostat (Advanced Research Systems), with a temperature range 10-800 K, that has an extremely low level of sample vibrations (tens of nm) and that is equipped by 18 wires for standard transport/electrical experiments, and 1 microwave cable for electrical experiments with frequencies up to 50 GHz, which enables us to combine optical and electrical experiments in devices. The time-resolved measurements can be performed using various techniques of ultrafast laser spectroscopy: pump-probe (measurement of transient absorption and reflection), time-resolved magneto-optical Kerr effect (TR MOKE), time-resolved photoluminescence, and laser-induced dynamic grating experiment (four-wave-mixing). These experiments can be performed with a simultaneous high spatial- (sub-micrometer) and time- (sub-picosecond) resolutions. Measurements of various linear and quadratic magneto-optical effects (magnetic circular dichroism, MCD, and birefringence, MCB, magnetic linear dichroism, MLD, and birefringence, MLB, with a simultaneous spatial- and spectral-resolutions can be performed in a home-made experimental setup that includes the closed-cycle helium cryostat and electromagnet (Walker Scientific, model HV-4H), which is generating magnetic field up to 1.5 T. The THz lab has custom-made time-domain THz spectroscopy setups (0.15-3 THz, 5-950 K, 0-7 T) based on a femtosecond laser oscillators (Coherent, Mira, Vitesse) and multi-THz air-based photonics (1-23 THz) powered by a femtosecond amplifier (Spectra-Physics, ACE). Additionally, the laboratory has a THz-SNOM (0.1-3 THz) with 30 nm resolution and with a pump-probe measurement option.