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107 results on '"Gorbunov, D.I."'

29. Acoustic signatures of the phase transitions in the antiferromagnet U2Rh2Sn

Author

Gorbunov, D.I., Andreev, A.V., Ishii, I., Prokes, K., Suzuki, T., Zherlitsyn, S., and Wosnitza, J.

Subjects
Condensed Matter::Strongly Correlated Electrons, U2Rh2Sn, ultrasound, antiferromagnetism, high magnetic field, crystal electric field
Abstract

We report on ultrasound measurements in a single crystal of the antiferromagnet U2Rh2Sn as a function of temperature and magnetic field. We find pronounced anomalies in the sound velocity at the N el temperature, 25 K, and at the field induced spin flop like transition at 22.5 T, which points to a strong magnetoelastic coupling. Additionally, we find that in the paramagnetic regime the temperature dependence of the magnetic susceptibility and the field dependences of the magnetization and sound velocity of transverse acoustic waves can be well described assuming a localized character of the 5f electrons. Using this premise, the crystal electric field scheme of U2Rh2Sn has been determined

Published
2020

30. Co NO3 2 as an inverted umbrella type chiral noncoplanar ferrimagnet

Author

Danilovich, I.L., Deeva, E.B., Bukhteev, K.Y., Vorobyova, A.A., Morozov, I.V., Volkova, O.S., Zvereva, E.A., Maximova, O.V., Solovyev, I.V., Nikolaev, S.A., Phuyal, D., Abdel Hafiez, M., Wang, Y.C., Lin, J.Y., Chen, J.M., Gorbunov, D.I., Puzniak, K., Lake, B., and Vasiliev, A.N.

Subjects
Condensed Matter::Strongly Correlated Electrons, Controlling collective states
Abstract

The low dimensional magnetic systems tend to reveal exotic spin liquid ground states or form peculiar types of long range order. Among systems of vivid interest are those characterized by the triangular motif in two dimensions. The realization of either ordered or disordered ground state in triangular, honeycomb, or kagome lattices is dictated by the competition of exchange interactions, also being sensitive to anisotropy and the spin value of magnetic ions. While the low spin Heisenberg systems may arrive to a spin liquid long range entangled quantum state with emergent gauge structures, the high spin Ising systems may establish the rigid noncollinear structures. Here, we present the case of chiral noncoplanar inverted umbrella type ferrimagnet formed in cobalt nitrate Co NO3 2 below TC 3K with the comparable spin and orbital contributions to the total magnetic moment

Published
2020

33. Anisotropic physical properties of single crystal U2Rh2Sn in high magnetic fields

Author

Prokes, K., Gorbunov, D.I., Reehuis, M., Klemke, B., Gukasov, A., Uhlirova, K., Fabreges, X., Skourski, Y., Yokaichiya, F., Hartwig, S., and Andreev, A.V.

Subjects
U2Rh2Sn, neutron diffraction, high magnetic fields
Abstract

We report on the crystal and magnetic structures,magnetic, transport, and thermal properties of U2Rh2Sn single crystals studied in part in high magnetic fields up to 58 T. The material adopts a U3Si2 related tetragonal crystal structure and orders antiferromagnetically below TN 25 K. The antiferromagnetic structure is characterized by a propagation vector k 0,0,1 2 . The magnetism in U2Rh2Sn is found to be associated mainly with 5f states. However, both unpolarized and polarized neutron experiments reveal at low temperatures in zero field non negligible magnetic moments also on Rh sites. U moments of 0.50 2 amp; 956;B are directed along the tetragonal axis while Rh moments of 0.06 4 amp; 956;B form a noncollinear arrangement confined to the basal plane. The response to applied magnetic field is highly anisotropic. Above amp; 8764;15 K the easy magnetization direction is along the tetragonal axis. At lower temperatures, however, a stronger response is found perpendicular to the c axis. While for the a axis no magnetic phase transition is observed up to 58 T, for the field applied at 1.8 K along the tetragonal axis we observe above 22.5 T a field polarized state. A magnetic phase diagram for the field applied along the c axis is presented.

Published
2017

39. Magnetic properties of DyFe5−xCoxAl7: Suppression of exchange interactions and magnetocrystalline anisotropy by Co substitution.

Author

Gorbunov, D.I., Andreev, A.V., Neznakhin, D.S., Henriques, M.S., Šebek, J., Skourski, Y., Daniš, S., and Wosnitza, J.

Subjects
*MAGNETIZATION, *INTERMETALLIC compounds, *FERMI energy, *COBALT, *FERRIMAGNETIC materials, *MAGNETIC fields
Abstract

In 3 d − 4 f intermetallic compounds, a Co substitution for Fe usually strengthens the exchange interactions due to a shift of the Fermi energy to a region of the 3 d band with higher density of states. Here, we study the influence of Co on the magnetism of ferrimagnetic DyFe 5 Al 7 using magnetization measurements in static (up to 14 T) and pulsed (up to 58 T) magnetic fields. We find that the homogeneity range of DyFe 5− x Co x Al 7 is limited to x ≤ 2.5 . The Co substitution for Fe produces a strong detrimental effect on the 3 d − 3 d intrasublattice exchange interactions, which leads to a pronounced decrease of the Curie temperature and of the 3 d − 4 f intersublattice exchange field. A reduction of the density of states at the Fermi level might occur due to a broadening of the 3 d band. A decrease of the rare-earth contribution to the magnetic anisotropy energy is also observed with increasing Co content. This is attributed to a competition between the Fe and Co contributions to the crystal electric field at the Dy site. [ABSTRACT FROM AUTHOR]

Published
2018
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49. Magnetization and magnetoacoustics of single-crystalline ErFe5Al7 in high magnetic fields.

Author

Gorbunov, D.I., Yasin, S., Andreev, A.V., Skourski, Y., Zherlitsyn, S., and Wosnitza, J.

Subjects
*MAGNETIZATION, *MAGNETOACOUSTICS, *MAGNETIC fields, *ACOUSTIC wave propagation, *CRYSTAL structure, *CURIE temperature
Abstract

Abstract: The magnetization and sound propagation in single-crystalline ErFe5Al7 (tetragonal crystal structure) have been studied in steady (up to 18T) and pulsed magnetic fields (up to 60T). The compound orders ferrimagnetically at a Curie temperature T C=201K and has a compensation point at T comp=34K. ErFe5Al7 displays a strong magnetic easy-plane anisotropy. A strong magnetic anisotropy is present as well within the basal plane; the [100] axis is the easy magnetization direction with a spontaneous magnetic moment M s=1.3µB/f.u. at 2K. Field-induced magnetic transitions, two along the [100] axis and two along the [110] axis, have been found in the vicinity of T=T comp. Changes in the magnetic state at the transitions result in significant alterations of the spin–phonon coupling, which is manifested by sharp anomalies in the sound velocity and sound attenuation. Along the easy [100] axis the forced ferromagnetic state is reached in a field of about 50 T at 2K, whereas along the [110] direction saturation is expected only above 60T. A magnetic field-temperature phase diagram has been extracted up to 60T. From the experimental data a value of n ErFe=3.3T/µB for the inter-sublattice Er–Fe exchange interaction has been obtained. [Copyright &y& Elsevier]

Published
2014
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50. Magnetic properties of single-crystalline TbFe5Al7.

Author

Gorbunov, D.I. and Andreev, A.V.

Subjects
*MAGNETIC properties of metals, *SINGLE crystals, *TERBIUM, *CRYSTAL structure, *IRON compounds, *ANISOTROPY, *FERRIMAGNETISM, *TEMPERATURE effect
Abstract

Highlights: [•] The TbFe5Al7 compound (tetragonal crystal structure) is ordered ferrimagnetically. [•] A magnetic study indicates that TbFe5Al7 displays strong easy plane anisotropy. [•] A spin-reorientation transition occurs within the basal plane near T = T comp. [•] TbFe5Al7 exhibits field-induced magnetization jumps in the vicinity of T = T comp. [•] Strong thermal and magnetic hysteresis is observed at low temperatures. [ABSTRACT FROM AUTHOR]

Published
2013
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