Search results

1

Magnetic Ordering in Boron-Rich Borides TbB_{66} and GdB_{66}

100%

Flachbart K., Gabani S., Mori T., Siemensmeyer K.

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issue 5

875-876

EN

Magnetic ordering in TbB_{66} and GdB_{66} was investigated at very low temperatures. Measurements of ac susceptibility have shown rather clear features of magnetic ordering below 1 K, at 0.34 K for TbB_{66} and at 0.20 K for GdB_{66}. However, no clear evidence of long range magnetic order was found by neutron scattering experiments. Reasons leading to these observations are discussed.

2

Phase Diagram of TmB_4 Probed by AC Calorimetry

76%

Kačmarčík J., Pribulová Z., Gabáni S., Samuely P., Siemensmeyer K., Shitsevalova N., Flachbart K.

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issue 5

903-904

EN

TmB_4 is a frustrated system based on the Shastry-Sutherland lattice that exhibits complex magnetic properties. In this contribution the magnetic field B vs. temperature T phase diagram of TmB_4 has been studied by ultrasensitive AC calorimetry in the temperature range between 2.9 and 12 K and in magnetic fields up to 8 T. Apart from already known phases our measurements have recognized several new phase transitions suggesting that the phase diagram of TmB_4 is even more complex and deserves further studies.

3

Magnetic Phase Diagram of TmB_{4} under High Pressure

76%

Gabáni S., Pristáš G., Takáčová I., Flachbart K., Filipov V., Shitsevalova N., Siemensmeyer K.

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vol. 126

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issue 1

356-357

EN

TmB_{4} is a Shastry-Sutherland frustrated system which exhibits very complex magnetic properties. In this contribution the phase diagram of magnetic field vs. temperature of TmB_{4} under hydrostatic pressure up to 26.5 kbar is investigated using sensitive ac-resistance measurements. Temperature and magnetic field dependences of resistance at various pressures were carried out in a piston cylinder pressure cell between 1.7 and 14 K and in magnetic fields up to 6 T. The obtained results exhibit shifts of ordering temperatures T_{N} as well as shifts of boundaries between different magnetic phases. The observed pressure dependences of T_{N} can be described by the relation d lnT_{N}/dp=+(0.16÷0.18) %/kbar. The effect of pressure on various interactions between magnetic ions in this compound is discussed.

4

Magnetocaloric Effect in Geometrically Frustrated Magnetic Compound HoB_{12}

76%

Snyman J., Flachbart K., Gabani S., Reiffers M., Shitsevalova N., Siemensmeyer K., Strydom A.

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issue 5

873-874

EN

The magnetocaloric effect of frustrated antiferromagnetic HoB_{12} is calculated. The isothermal entropy change Δ S characterising the magnetocaloric effect shows a small positive change upon magnetisation below the transition temperature T_{N}, indicating a small inverse magnetocaloric effect. At T_{N}, Δ S shows clear scaling behaviour with the applied magnetic field. The adiabatic temperature change Δ T shows paramagnetic behaviour above T_{N}, despite strong magnetic correlations that persist in this temperature region. The adiabatic temperature change calculated for HoB_{12} is appreciable.

5

Phonon Drag and Magnetic Anomalies of Thermopower in RB_{12} (R = Ho, Er, Tm, Lu)

64%

Glushkov V., Demishev S., Ignatov M., Khayrullin E., Sluchanko N., Shitsevalov N., Levchenko A., Filipov V., Flachbart K., Siemensmeyer K.

Acta Physica Polonica A

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2008

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vol. 113

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issue 1

275-278

EN

High precision measurements of the Seebeck coefficient S(T) were carried out on the single crystals of RB_{12} (R = Ho, Er, Tm, Lu) at temperatures 2-300 K. It was shown that the effects of phonon drag result from vibrations of rare earth ions (ħω_E≈10-33 meV) in the rigid framework structure of the B_{12} clusters and determine the main contribution to thermopower at intermediate temperatures (30-300 K). The correlated behavior of transport parameters favors the appreciable enhancement of spin fluctuations in the sequence of magnetic compounds (HoB_{12}-TmB_{12}) when approaching to the valence instability state in YbB_{12}. The giant increase in S(T) detected in the vicinity of the Néel temperature T_N for HoB_{12}, ErB_{12}, and TmB_{12} seems to result from the density of states renormalization caused by antiferromagnetic ordering.

6

Magnetic Structure and Phase Diagram of TmB_4

64%

Gabáni S., Maťaš S., Priputen P., Flachbart K., Siemensmeyer K., Wulf E., Evdokimova A., Shitsevalova N.

Acta Physica Polonica A

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2008

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vol. 113

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issue 1

227-230

EN

Magnetic structure of single crystalline TmB_4 has been studied by magnetization, magnetoresistivity, and specific heat measurements. A complex phase diagram with different antiferromagnetic phases was observed below T_{N1}=11.7 K. Besides the plateau at half-saturated magnetization (1/2 M_S), also plateaus at 1/9, 1/8 and 1/7 of M_S were observed as a function of applied magnetic field Bparallel c. From additional neutron scattering experiments on TmB_4, we suppose that these plateaus arise from a stripe structure which appears to be coherent domain boundaries between antiferromagnetic-ordered blocks of 7 or 9 lattice constants. The received results suggest that the frustration among the Tm^{3+} magnetic ions, which maps to a geometrically frustrated Shastry-Sutherland lattice, leads to a strong competition between antiferromagnetic and ferromagnetic order. Thus, stripe structures in intermediate field appear to be the best way to minimize the magnetostatic energy against other magnetic interactions among the Tm ions combined with very strong Ising anisotropy.

7

Bulk and Local Magnetic Susceptibility of ErB_{12}

52%

Bogach A., Bogomolov L., Glushkov V., Demishev S., Sluchanko D., Sluchanko N., Shitsevalova N., Levchenko A., Filipov V., Flachbart K., Siemensmeyer K.

Acta Physica Polonica A

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2008

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vol. 113

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issue 1

271-274

EN

High precision measurements of magnetoresistance Δρ/ρ = f(T,H) and magnetization M(T,H) were carried out on single crystals of rare-earth dodecaboride ErB_{12} at temperatures in the interval 1.8-30 K in magnetic fields up to 70 kOe. The high accuracy of the experiments allowed us to perform numerical differentiation and analyze quantitatively the behavior of the derivative d(Δρ/ρ)/dH = f(T,H) and of the magnetic susceptibility χ(T,H) = dM/dH in paramagnetic and magnetically ordered (antiferromagnetic, T_N ≈ 6.7 K and T_M ≈ 5.85 K) phases of ErB_{12}. It was shown that negative magnetoresistance anomalies observed in present study in paramagnetic state of ErB_{12} may be consistently interpreted in the framework of a simple relation between resistivity and magnetization -Δρ/ρ ~ M^2.

8

Anisotropy of Magnetoresistance in HoB₁₂

52%

Khoroshilov A., Krasnorussky V., Bogach A., Glushkov V., Demishev S., Levchenko A., Shitsevalova N., Filipov V., Gabáni S., Flachbart K., Anisimov M., Siemensmeyer K., Sluchanko N.

Acta Physica Polonica A

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2017

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vol. 131

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issue 4

976-978

EN

We present results of precision measurements of magnetoresistance of isotopically pure Ho¹¹B₁₂ at low temperatures 2÷10 K in magnetic field up to 80 kOe of different orientation to the crystal axes. The data obtained revealed strong anisotropy of magnetoresistance and allowed us to reconstruct magnetic H-T phase diagrams for main crystallographic directions H || [001], [110], and [111]. Analysis of magnetoresistance derivatives allowed to conclude in favor of two main magnetoresistance contributions. Among of them the negative quadratic component is attributed to charge carriers scattering on a magnetic clusters of Ho³⁺ ions (4f component) and positive linear one may be explained in terms of scattering on a spin density waves (5d component).

9

Neutron and EPR Study of Cu(tn)Cl_{2} - a~Two-Dimensional Spatially Anisotropic Triangular-Lattice Antiferromagnet

52%

Tarasenko R., Orendáčová A., Čižmár E., Maťaš S., Orendáč M., Zeleňák V., Pavlík V., Siemensmeyer K., Zvyagin S., Wosnitza J., Feher A.

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vol. 126

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issue 1

232-233

EN

We have studied the temperature dependence of the lattice parameters and the influence of spin anisotropy on the electron paramagnetic spectra of Cu(tn)Cl_2, an S=1/2 quasi-two-dimensional spatially-anisotropic triangular-lattice Heisenberg antiferromagnet. The variation of the resonance fields with temperature reflects the presence of an easy-plane exchange anisotropy with J_{z}/J_{x,y}<1 and g-factor anisotropy, g_{z}/g_{x,y}>1.

Refine search results

Magnetic Ordering in Boron-Rich Borides TbB_{66} and GdB_{66}

Phase Diagram of TmB_4 Probed by AC Calorimetry

Magnetic Phase Diagram of TmB_{4} under High Pressure

Magnetocaloric Effect in Geometrically Frustrated Magnetic Compound HoB_{12}

Phonon Drag and Magnetic Anomalies of Thermopower in RB_{12} (R = Ho, Er, Tm, Lu)

Magnetic Structure and Phase Diagram of TmB_4

Bulk and Local Magnetic Susceptibility of ErB_{12}

Anisotropy of Magnetoresistance in HoB₁₂

Neutron and EPR Study of Cu(tn)Cl_{2} - a~Two-Dimensional Spatially Anisotropic Triangular-Lattice Antiferromagnet