The Institute

The Division is studying (both experimentally and theoretically) phenomena in highly correlated electron systems, namely, those in which the localized f electrons  interact strongly with the electrons from the conduction band. These are compounds, in which at least one component is an element having partially populated the f electron shell, namely lanthanides or actinides. In the Department of Magnetic Research, mostly compounds based on cerium, iterbium and uranium are studied. Compounds based on other lantanides and actinides are also examined, however, they represent a minority in a number of research projects carried out by the Department.

The head of the department is Prof. Dr. Piotr Wisniewski.

Research:

• Unconventional superconductivity and quantum critical phenomena in heavy-fermion systems.
• Topologically nontrivial electronic states in semimetals and semiconductors with narrow energy gap.
• Dualism of 5f electrons in the intermetallic uranium compounds.
• Quantum many-body phenomena in arsenic skutterudites.
• The influence of quantum interference on transport properties of intermetallic compounds of d- and f-electrons with large structural disorder.
• Transformation of the Fermi surface (Lifshitz type) in systems with cage structure and strongly correlated electrons.
• Anomalous thermodynamic and transport properties of metallic systems with strong electron correlations, determined by effects of localized states and the conduction band hybridization.
• Orbital Kondo effect resulting from structural two-level systems.
• Theoretical description of the effect of localized electrons on spectroscopic, thermal, magnetic and transport properties of solids.
• The influence of hydrogenation on the magnetic properties and magnetic phase transitions in pure rare earth metals and their compounds with transition metals.
• Materials and technologies for advanced storage systems and energy conversion.

A direct consequence of the partial filling of the f shell is the possibility of localized of magnetic moments in the tested compounds and their spontaneous organization in a (usually very low) temperature. Interactions leading to the order areaccompanied by the interactions that destroy that order. The competition of these two processes results in the presence of a wide range of poorly studied physical phenomena such as the formation of superheavy quasiparticles (i. e. heavy fermions), unconventional superconductivity, or non-Fermi liquid behavior. A detailed description of these phenomena cannot be found in academic textbooks and their description is one of the major challenges of modern solid state physics.

A more complete description of the research topics of the magnetic research group can be found here: MORE...

The Division also specializes in experimental and theoretical studies of electron transport phenomena occurring in single crystals of lanthanum compounds and actinides. Among lanthanide compounds a lot of attention is paid to the ones in which the Kondo effect, splitting of the 4f states in the crystalline field as well as magnetic and quadrupole ordering have a visible impact on the properties of electronic transport. Of high interest are also regular LaMe₃ compounds as well as filled arsenide scutterudites arsenic - LaT₄As₁₂ (La - lanthanide; Me - Sn, Pb, In, Ga, T - Fe, Ru, Os). Arsenide scutterudites filled with a lanthanide have been obtained in the Division in the form of single crystals for the first time in the world. These arsenide scutterudites, like the previously studied by other authors filled phosphoride and antimonide scutterudites  (the so-called thermoelectric rattles), have a great wealth of physical properties that are the driving force behind the scientific and technological interest. Research of actinide compounds led the Division to detection of the existence of:

1. non-magnetic Kondo effect of structural defects in crystals, both diamagnetic thorium pnictochalcogenides and ferromagnetic uranium pnictochalcogenides
2. ferromagnetic semiconductor (Th_xU_1-x)₃As₄ with potentially interesting spintronic properties.

As one of the few in Poland,  for many years the Division has specialized in studies of NMR of nuclei of s, p and d-electron elements in alloys and intermetallic compounds. These hydrides and borides of transition metals and intermetallic compounds of these elements involving rare earth and uranium, which are extremely important from the point of view of their practical applications. They show a great wealth of physical properties: from the semiconductor nature to magnetic, quadrupole ordering or heavy-fermion properties. It has been recently shown that the use of techniques of high-speed rotation at the magic angle (MAS) at the resonance of "heavy" nuclei ¹¹⁹Sn and ¹⁹⁵Pt allows to obtain multiplet structure of the spectra of resonant compounds TiPtSn and ZrPtSn, thereby detecting the effects of scalar and covalent nature of the chemical bonds in these compounds. On the other hand, studies using a "light" core ¹¹B in a number of borides: YB₄, YB₆, YB₁₂, ZrB₁₂, or 12 allowed to determine the size of components of the electric field gradient (GPE) tensor in boron atoms positions. These values have allowed to validate theoretical calculations of the electronic structure, which lay down the GPE tensor for these compounds.

Another specialty of the Division is the work on metal hydrides:

1. Low- and high-pressure synthesis of new hydride phases.
2. Investigation of the effect of hydrogen on the structural and magnetic properties of complex intermetallic compounds of rare earth with d-metals.
3. Studies on the properties of hydrogen absorption by Mg-Ni alloys synthesized using mechnical milling.
4. Characterization of hydride systems using method for testing the pressure equilibrium isotherms as a function of the concentration of hydrogen.
5. Studies of thermodynamic properties of the MAX d-metal triple carbide phases using low-temperature calorimetry.

Important publications in 2005-2015:

• R. Troć, Z. Gajek, and A. Pikul: Dualism of the 5f Electrons of the Ferromagnetic Superconductor UGe₂ as Seen in Magnetic, Transport, and Specific-Heat Data. Phys. Rev. B 86 (2012) 224403 (14).
• T. Cichorek, A.Sanchez, P. Gegenwart, F. Weickert, A. Wojakowski, Z. Henkie, G. Auffermann, S. Paschen, R. Kniep, and F. Steglich: Two- Channel Kondo E ect in Glasslike ThAsSe. Phys. Rev. Lett . 94 (2005) 236603 (4).
• V.H. Tran, W. Miiller, and Z. Bukowski: Observation of Spin-Gap in the Normal State of Superconductor Mo₃Sb₇. Phys. Rev. Lett. 100 (2008) 137004 (4).
• O. Pavlosiuk, D. Kaczorowski, and P. Wiśniewski: Shubnikov–de Haas Oscillations, Weak Antilocalization Effect and Large Linear Magnetoresistance in the Putative Topological Superconductor LuPdBi. Sci. Rep. 5 (2015) #9158 (9).
• D. Kaczorowski, A.P. Pikul, D. Gnida, and V.H. Tran: Emergence of a Superconducting State from an Antiferromagnetic Phase in Single Crystals of the Heavy-Fermion Compound Ce₂PdIn₈. Phys. Rev. Lett. 103 (2009) 027003 (4).
• B. Nowak, O. Pavlosiuk, and D. Kaczorowski: Band Inversion in Topologically Nontrivial Half-Heusler Bismuthides: ²⁰⁹Bi NMR Study. J. Phys. Chem. C 119 (2015) 2770−2774.
• H. Drulis, A. Hackemer, P. Głuchowski, K. Giza, L. Adamczyk, and H. Bala: Gas Phase Hydrogen Absorption and Electrochemical Performance of La₂(Ni,Co,Mg,M) Based Alloys. Int. J. Hydrogen Energy 39 (2014) 2423−2429. 
• M. Szlawska, D. Gnida, and D. Kaczorowski: Magnetic and Electrical Transport Behavior in the Crystallographically Disordered Compound U₂CoSi₃. Phys. Rev. B 84 (2011) 134410 (8). 
• R.E. Baumbach, P.C. Ho, T.A. Sayles, M.B. Maple, R. Wawryk, T. Cichorek, A. Pietraszko, and Z. Henkie: The Filled Skutterudite CeOs₄As₁₂ : A Hybridization Gap Semiconductor. Proc. Nat. Acad. Sci. USA 105 (2008) 17307−17311. 
• P. Swatek, M. Daszkiewicz, and D. Kaczorowski: Paramagnetic Heavy-Fermion Ground State in Single-Crystalline UIr₂Zn₂₀. Phys. Rev. B 85 (2012) 094426 (8).

Apparatus:

Synthesis of materials in the form of high-quality single crystals, polycrystals and powders:

• MBraun glove boxes with ultra-pure argon atmosphere, with accurately monitored residual content of oxygen and water vapors (<0.1 ppm).
• Hünger induction furnace, coupled with a pyrometer and programmable temperature controller, used to melting metals in a precisely controlled temperature,
• Netzsch Jupiter 3 thermal analyzer with a thermobalance and a tungsten furnace for simultaneous differential thermal (DTA) and thermogravimetric (TGA) analysis - 20°C to 2400°C,
• GES Corp. four-arc furnace for single crystal growth using the Czochralski method,
• station for single crystal growth by Bridgman method,
• graphite furnace for growing single crystals by mineralization method in temperatures up to 2400°C,
• the pressure chambers for the preparation of single crystals under a pressure of 60 atm and in temperatures up to 900°C,
• low and high pressure chambers for the synthesis of hydride phases under a hydrogen gas pressure up to 50 atm and temperature of 400°C, and determination of equilibrium characteristics: pressure-temperature-composition and the basic thermodynamic functions of the metal-hydrogen bond.

Physical properties measurements:

• Quantum Design SQUID magnetometer with horizontal and vertical rotators, used to precisely determine the magnetization and magnetic susceptibility of single- and polycrystalline samples, thin films and powders in the temperature range 1.7-800 K and magnetic fields 0-5.5 T,
• Quantum Design measuring platform (PPMS), equipped with a 3He refrigerator, used for measuring the heat capacity, electrical resistance, Hall coefficient, the critical current in superconductors, and current-voltage characteristics of semiconductors in the temperature range 0.33-400 K and magnetic fields 0-9 T,
• Several stations for measurement of transport properties (electrical resistance, thermopower and thermal conductivity) in the temperature range 1.5-300 K and magnetic fields 0-8 T.

Theoretical research:

• Commercial software package for the numerical determination of the electronic structure using DFT method,
• In-house developed software packages for numerical determination of electronic structure using "ab initio" methods.

Electronic transport:

• Installations (in-house designed) to examine the electrical resistance, magnetoresistance, Hall effect, thermoelectric and strength at temperatures from 4.2 K to 300 K and in fields up to 1 T with the possibility of changing the direction of the field during the measurements.
• Unipress gas compressor with chambers for testing electrical resistance, magnetoresistance and Hall effect under hydrostatic pressure up to 1 GPa, and in the fields of 1 T.
• Liquid chamber (Japanese production) for tests under pressure of 3 GPa.
• He3 refrigerator with a cryostat for testing transport coefficients in temperatures from 0.4 K to 300 K and in fields up to 7 T
• Equipment for the preparation of crystals: Malvern Czochralski crystal grown system, in-house installations for single crystal growth using flux and chemical transport methods at ambient pressure and in temperatures up to 1100°C.
• Pressure chambers for the preparation of single crystals under pressure of 60 atm and in temperatures up to 900°C.

Besides, the Division is in charge of:

• Laboratory of Low Temperatures with two dilution refrigerators,
• MBRAUN LABMASTER 130 manipulation chamber for work in oxygen-free atmosphere.

Magnetic nuclear resonance:

• Bruker (Germany) Avance DSX 300 pulse spectrometer with 7 T superconducting magnet with probes allowing for the detection of signal from 109Ag to 31P nuclei in the temperature range 150 - 400 K, CP MAS probe for 17O to 31P nuclei for the temperature range 170 - 400 K; maximum rotational frequency of 12 kHz, diameter of the tubes - 4 mm; probe for 1H in the temperature range 4 - 300 K, the probe for 17O to 31P nuclei in the temperature range 4.2 - 300 K. The spectrometer is dedicated to the measurement of solids,
• Station for measuring the specific heat of single- and polycristalline samples in the temperature range: 2.6 - 70 K and possibly in the magnetic field of 1 - 7 T.

Metal hydrides:

• Low-pressure apparatus for synthesis of hydride phases.
• The ability to synthesize hydride phases in hydrogen at pressure of p < 1 atm and in temperatures up to 900°C. Sample weight m > 100 mg.
• The possibility of synthesizing hydride phases under a hydrogen gas pressure to p < 50 atm and temperatures up to 400°C. Sample weight 1g < m < 5g. The equipment allows the recording equilibrium pressure-temperature-composition characteristics to determine the phase diagram and the basic thermodynamic properties of a metal-hydrogen system.
• Laboratory of Electron Paramagnetic Resonance spectroscopy - X-band (9.5 GHz). Measurement capabilities: EPR spectra of all resonance active paramagnetic objects in temperature range from 4.3 K to 300 K.
• Laboratory of Mössbauer spectrometry. Measurement capabilities: recording and analysis of Mössbauer spectra of resonant ⁵⁷Fe and ¹¹⁹Sn nuclei in the temperature range 15 K < T < 1000 K (currently off-duty).
• Laboratory of Low Temperature Calorimetry. Computerized measurements of specific heat of solids. Capabilities: test rig used to measure the specific heat of solid and powder samples in the temperature range from 3 K to 270 K. The active volume of the sample of about 0.7 cm³. Duration of measurement -- about 7 days.

Staff: