TY - JOUR

T1 - Structural and magnetic properties of YAl3(BO3)4 and EuAl3(BO3)4 single crystals doped with Co2+

AU - Прохоров, Андрей

AU - Черныш, Лариса

AU - Minyakaev, R.

AU - Мазур, Антон Станиславович

AU - Zajarniuk, T.

AU - Szewczyk, A.

AU - Dyakonov, V.

AU - Lančok, J.

AU - Прохоров, Александр

N1 - Funding Information: The research was supported by SAFMAT LM2015088 project and Ministry of Education, Youth and Sports of Czech Republic Project no. LO1409 . The Authors wish to thank Dr.P.Aleshkevych, Dr.A.Nabialek for assistance when carrying out an experiment.

PY - 2018/6/15

Y1 - 2018/6/15

N2 - Structural and magnetic properties of the cobalt-doped YAl 3(BO 3) 4 and EuAl 3(BO 3) 4 crystals were studied using electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), X-ray diffraction analysis, and specific heat methods. It was found that cobalt, when doped to the studied crystals, is in divalent state, substitutes the aluminum ions and forms a system of three magnetically equivalent magnetically nonequivalent centers whose magnetic axes are rotated at 120° relative to one another. We have determined parameters of the spin Hamiltonian of orthorhombic symmetry, describing the anisotropic angular dependence EPR spectra for both types of crystals. Strong broadening of EPR lines is caused by the spin-lattice relaxation. Specific heat of the EuAl 3(BO 3) 4 and YAl 3(BO 3) 4 crystals doped with 0.2% of Co 2+ was measured over the temperature range from 3 to 395 K, in zero magnetic field. The Debye temperature was determined to be equal to 355К and 358 K for YAl 3(BO 3) 4 and EuAl 3(BO 3) 4, respectively. Crystallographic structure at ambient conditions as well as variations of unit-cell parameters and thermal expansion coefficients with temperature were studied in detail in the range 302 K < T < 1073 K. NMR study on 27Al and 11B nuclei at room temperature was conducted. It is shown that on changing the rare-earth ion from yttrium to europium, the contribution of hyperfine interactions to the resonance characteristics of the samples increases. It is also shown that there are two nonequivalent environments of boron atoms with an attitude close to 1.1 and 1.2 for the samples containing 0.1 and 0.2% of cobalt ions, respectively.

AB - Structural and magnetic properties of the cobalt-doped YAl 3(BO 3) 4 and EuAl 3(BO 3) 4 crystals were studied using electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), X-ray diffraction analysis, and specific heat methods. It was found that cobalt, when doped to the studied crystals, is in divalent state, substitutes the aluminum ions and forms a system of three magnetically equivalent magnetically nonequivalent centers whose magnetic axes are rotated at 120° relative to one another. We have determined parameters of the spin Hamiltonian of orthorhombic symmetry, describing the anisotropic angular dependence EPR spectra for both types of crystals. Strong broadening of EPR lines is caused by the spin-lattice relaxation. Specific heat of the EuAl 3(BO 3) 4 and YAl 3(BO 3) 4 crystals doped with 0.2% of Co 2+ was measured over the temperature range from 3 to 395 K, in zero magnetic field. The Debye temperature was determined to be equal to 355К and 358 K for YAl 3(BO 3) 4 and EuAl 3(BO 3) 4, respectively. Crystallographic structure at ambient conditions as well as variations of unit-cell parameters and thermal expansion coefficients with temperature were studied in detail in the range 302 K < T < 1073 K. NMR study on 27Al and 11B nuclei at room temperature was conducted. It is shown that on changing the rare-earth ion from yttrium to europium, the contribution of hyperfine interactions to the resonance characteristics of the samples increases. It is also shown that there are two nonequivalent environments of boron atoms with an attitude close to 1.1 and 1.2 for the samples containing 0.1 and 0.2% of cobalt ions, respectively.

KW - Aluminum borates

KW - EPR

KW - Low-spin state

KW - Multiferroics

KW - NMR

KW - PPMS

KW - RAB

KW - Rare-earth

KW - Spin Hamiltonian parameters

KW - Superposition model

KW - X-ray diffraction

KW - SOLID-STATE NMR

KW - LASER

KW - EPR-SPECTRA

KW - YTTRIUM

KW - GD3+ ION

KW - LOW-SYMMETRY ASPECTS

KW - ELECTRON-PARAMAGNETIC-RESONANCE

KW - CR3+

KW - FIELD SPLITTING PARAMETERS

KW - MN2+ IONS

UR - http://www.scopus.com/inward/record.url?scp=85049342471&partnerID=8YFLogxK

UR - http://www.mendeley.com/research/structural-magnetic-properties-yal3bo34-eual3bo34-single-crystals-doped-co2

U2 - 10.1016/j.jallcom.2018.06.149

DO - 10.1016/j.jallcom.2018.06.149

M3 - Article

VL - 765

SP - 710

EP - 720

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

SN - 0925-8388

ER -