[en] Using Mossbauer spectroscopy on ¹⁷⁰Yb, we detected two low temperature phase transitions in the heavy electron pnictide YbSb. Below T_N= 0.32K antiferromagnetic ordering of Yb³⁺ develops, and between 0.32K and 5K a phase exists whose nature is yet undetermined. Magneto-transport measurements confirm the heavy electron properties and the 5K phase transition

[en] We measured the magnetoresistance of a two-dimensional electron gas in a strongly disordered silicon MOSFET system in the presence of a parallel magnetic field up to 40 T. We observe resistance saturation for magnetic fields larger than the calculated magnetic field for fully spin-polarized electron gas. Our experimental results on the magnetoresistance can be quantitatively described by a transport theory taking into account screening and finite width effects in a spin-polarized electron gas

[en] By means of high-pulsed magnetic field up to μ₀H=32 T we have studied HoBaCo₂O_5+δ (δ=0.52(1)). The high-field M(H) integrated curves evidence a magnetic field-induced phase transition visible from about T=75 to 275 K. The obtained results are compared with the field-induced transition found for GdBaCo₂O_5+δ (with δ=0.54(2)). The jump of the magnetization at the field-induced transition is independent of the rare earth at this level of oxygen content. In contrast, we have observed larger values of the critical field, and that the transition persists up to higher temperature, when reducing the rare-earth size. This indicates that the low-temperature antiferromagnetic phase becomes more stable when the size of the rare earth is reduced

[en] Doped perovskite manganites Ln_1-x(Ca,Sr)_xMnO₃ are characterised by strong interplay of electron, lattice and spin degrees of freedom. Its ground state ranges from antiferromagnetic insulator to a ferromagnetic metal and strongly depends on many parameters such as temperature, external field, chemical composition, oxygen isotope content, etc. In this work magnetic properties of the compound Sm_1-xSr_xMn¹⁶O₃ together with its isotopically substituted counterpart Sm_1-xSr_xMn¹⁸O₃ (90% of ¹⁸O₂) were studied under magnetic field up to 35 T in the temperature range 4-250 K. We have performed magnetisation and susceptibility isothermal field scans alongside with study of transport properties. Several sharp magnetic phase transitions were observed, and H-T phase diagram was reconstructed. It was found that oxygen isotope substitution ¹⁶O→¹⁸O significantly modifies the phase diagram in such a way, that the transition fields shift up to the higher values in the samples with the heavier oxygen masses

[en] The band structure of Cd₃P₂ is presented on the basis of Bodnar's model which is extended by Wallace in presence of magnetic field. The oscillations of the Fermi level with magnetic field are calculated and it is found that the amplitude of the oscillations in Cd₃P₂ is larger than in Cd₃As₂. The effect of the so-called free-electron term is included in the calculation of the g-factor and cyclotron effective mass. The correction due to the free-electron term in the g-factor is smaller (g_f << 2) than anticipated and depends on energy. Another interesting result of the calculation is that there is linear relationship between cyclotron effective mass and energy. (author)

[en] We investigated the stability of the charge ordering phases of Ln_1/2Ca_1/2MnO₃ (Ln=La, Pr, Nd, Sm, Y, and Ho) and Bi_1/4Ca_3/4MnO₃. Except for Y and Ho, the magnetisation measurements showed a magnetic-field-induced transition which collapse the antiferromagnetic or paramagnetic charge ordering phase to a ferromagnetic phase. H-T phase diagrams were defined

[en] Measurements of magnetic susceptibility χ as a function of temperature T and of magnetisation M as a function of applied magnetic field H at a number of fixed temperatures were made on polycrystalline samples of Cu₂FeGeSe₄. The χ versus T data show that an antiferromagnetic transition occurs at 20 K and that a second transition occurs at ∼8 K, indicating a transition to weak ferromagnetic form. The M versus H curves indicated that at all temperatures below ∼70 K bound magnetic polarons (BMP) occur, in the paramagnetic, antiferromagnetic and weak ferromagnetic ranges. Below 8 K, the M versus H curves exhibited magnetic hysteresis, and this is attributed to the interaction of the BMPs with tetragonally anisotropic matrix. The B versus H curves were well fitted by a Langevin-type of equation, and the variation of the fitting parameters determined as a function of temperature. These showed that above 20 K the total BMP magnetisation fell almost linearly with increasing temperature and effectively disappeared at 70 K. The number of BMPs remained practically constant with temperature having a mean value of 6.55x10¹⁸/cm³. The analysis gave a value of 213 μ_B for the average magnetic moment of a BMP, corresponding to 42.4 Fe atoms. Using a simple spherical model, this gives the radius of a BMP as 12.0 A

[en] The magnetic phase diagram of MnGa₂Se₄ was obtained by means of low magnetic field susceptibility in the temperature range from 2 to 300 K and high magnetic field magnetization measurements at several temperatures between 2 and 150 K, by using a MPMS-5 magnetometer and pulsed magnetic fields method, respectively. The obtained results show that the phase diagram is consistent with the uniaxial antiferromagnetic material when the field is applied parallel to the easy axis

[en] We present a comparative investigation under field of three Bi_1-xSr_xMnO₃ manganites in the low-doping regime (x≤0.50). Powdered samples were investigated in pulsed fields up to 35, 50 or 130 T depending on the compound (x=0.25, 0.33, 0.50). Remarkable differences are found in the M(H) curves when comparing the response to the magnetic field of the two different charge-order phases

[en] A comparative investigation of the charge modulation tendencies in R-M-MnO₃ and Bi-Sr-MnO₃ manganites reveals remarkable differences in these series of materials. By means of magnetic, magnetotransport, synchrotron X-ray and neutron diffraction, as well as pulsed high magnetic fields data, we compare the systematic electronic and magnetic properties of several rare-earth-based manganites and bismuth-based Sr manganites. The differences between these types of systems are rationalized in terms of the role that the different electronic structure of bismuth and rare earth plays in these materials