Field induced structural phase transition in layered compounds MR(MoO4)2 (M = K, Cs; R = Er, Tm)

Khatsko, E. N.; Kobets, M. I.; Pereverzev, J. V.

doi:10.1080/00150199908016999

Cited by 6 publications

(6 citation statements)

References 4 publications

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“…Increasing the magnetic field further generates the CEF level crossing at 25 T observed in the magnetization measurements. This field-induced sequence of transitions is consistent with the extremely low energy gap ∆ = 1.6 meV between the CEF ground state doublet and first excited state 47 . Therefore, a pseudo Jahn-Teller distortion incorporating the J z = 15 2 and J z = 13 2 CEF levels, as illustrated in Figure 8, is a viable mechanism for inducing ferroelectricity in this material.…”

Section: Discussionsupporting

confidence: 83%

Magnetoelectric effect arising from a field-induced pseudo Jahn-Teller distortion in a rare-earth magnet

Lee

Chen

Choi

et al. 2020

Phys. Rev. Materials

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Magnetoelectric materials are attractive for several applications, including actuators, switches, and magnetic field sensors. Typical mechanisms for achieving a strong magnetoelectric coupling are rooted in transition metal magnetism. In sharp contrast, here we identify CsEr(MoO4)2 as a magnetoelectric material without magnetic transition metal ions, thus ensuring that the Er ions play a key role in achieving this interesting property. Our detailed study includes measurements of the structural, magnetic, and electric properties of this material. Bulk characterization and neutron powder diffraction show no evidence for structural phase transitions down to 0.3 K and therefore CsEr(MoO4)2 maintains the room temperature P2/c space group over a wide temperature range without external magnetic field. These same measurements also identify collinear antiferromagnetic ordering of the Er 3+ moments below TN = 0.87 K. Complementary dielectric constant and pyroelectric current measurements reveal that a ferroelectric phase (P ∼ 0.5 nC/cm 2 ) emerges when applying a modest external magnetic field, which indicates that this material has a strong magnetoelectric coupling. We argue that the magnetoelectric coupling in this system arises from a pseudo Jahn-Teller distortion induced by the magnetic field.

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Section: Discussionsupporting

confidence: 83%

Magnetoelectric effect arising from a field-induced pseudo Jahn-Teller distortion in a rare-earth magnet

Lee

Chen

Choi

et al. 2020

Phys. Rev. Materials

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“…The field dependence for this orientation does not exhibit any hysteresis when increasing and decreasing magnetic field. This finding is in disagreement with results of Khastko et al 4 The field dependence of the b-axis magnetization measured with increasing and decreasing field shown in Fig. 3 exhibits weak hysteresis at 4.2 K. At lower or higher temperatures no hysteresis could be discerned.…”

Section: A Magnetization and Magnetic Susceptibility Of Ker(moo 4 )contrasting

confidence: 87%

“…1-4͒ suggest that the magnetic phase transition to an antiferromagnetic ͑AF͒ ordered state takes place at T N = 0.95 K Ϯ 0.01 K. According to Khatsko et al, 3 KEr͑MoO 4 ͒ 2 system does not exhibit a spontaneous Jahn-Teller effect on cooling down to 0.5 K in zero field, however, in paramagnetic region above T N considerable changes in magnetic properties connected with the structural phase transitions are induced by moderate fields. 4 Below T N , a noncollinear zero-field AF structure, in Refs. 1 and 2 named as 6AF-12, with magnetic moments lying in the ac plane and having an angle of about 9°with respect to the c-axis direction has been suggested by Anders et al This, however, has been suggested on the basis of theoretical calculations and electron-paramagnetic-resonance experiments only.…”

Section: Introductionmentioning

confidence: 99%

Neutron diffraction study on the two-dimensional Ising systemKEr(MoO4)2

et al. 2010

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The magnetic properties of the two-dimensional Ising antiferromagnet KEr͑MoO 4 ͒ 2 have been investigated below and above transition temperature T N ϳ 0.95 K in zero field and in fields up to 6.5 T by means of elastic neutron-diffraction, heat-capacity, and magnetization measurements. The low-temperature signal recorded at 0.34 K by neutron diffraction is explained within a noncollinear magnetic structure model. However, additional contribution is also present when applying the external magnetic field along the c axis even at temperatures well above the magnetic transition temperature T N . Various explanations are discussed.

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“…The electronic spectrum of rare-earth ions in the crystalline field usually has lowlying excited levels, and that leads to the possibility of reorganization of the corresponding electronic states both by an external magnetic field and by displacements of the ions. This is responsible, in particular, for the magneticfield-induced structural phase transitions observed in various compounds of this class [1][2][3][4][5]. In the case of nonKramers rare-earth ions the lowest electronic state often form a quasi-doublet with a gap Δ of the order of few K, well separated from the rest of the spectrum.…”

mentioning

confidence: 99%

“…The measurements were carried out with a SQUID magnetometer developed at the Institute Néel equipped with a miniature 3 He- 4 He dilution refrigerator allowing measurements down to 70 mK.…”

mentioning

confidence: 99%

Evidence for low-temperature antiferromagnetic phase transition in Ising singlet magnet KTb(WO4)2

Khatsko

Paulsen

Rykova

2011

Low Temperature Physics

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The magnetic susceptibility and magnetization measured along the b axis of a KTb(WO 4 ) 2 single crystal was investigated experimentally in the temperature range 70 mK-6 K and in magnetic fields up to 8 T. The results allow us to make conclusion that singlet magnet KTb(WO 4 ) 2 undergoes an antiferromagnetic phase transition T c = 0.65 K. Alkali-rare-earth double molybdates and tungstates have been actively studied for a long time. Many compounds of this class are characterized by a strong magnetic anisotropy of the rare-earth ions, a low local symmetry, and a pronounced chain structure. The electronic spectrum of rare-earth ions in the crystalline field usually has lowlying excited levels, and that leads to the possibility of reorganization of the corresponding electronic states both by an external magnetic field and by displacements of the ions. This is responsible, in particular, for the magneticfield-induced structural phase transitions observed in various compounds of this class [1][2][3][4][5]. In the case of nonKramers rare-earth ions the lowest electronic state often form a quasi-doublet with a gap Δ of the order of few K, well separated from the rest of the spectrum. The magnetic dipole and exchange interactions in these compounds are of the same order of magnitude. Therefore, singlet and excitonic types of magnets can be realized in these compounds (in the second case the interactions are insufficient to induce magnetic order suppressed by the gap Δ [6,7]. In the non-Kramers doublet case the contribution to the magnetic properties of the crystal from the higher-lying excitations of the rare-earth ions are also unusual [6]. All of these circumstances cause great interest to the study of such systems. Here it is possible to study a number of topical questions in solid state physics in a comparatively simple situation. Among such topics are the interaction of electronic excitations with lattice vibrations (the JahnTeller effect, polaron effects, etc.), structural phase transitions taking place by unusual scenarios (incommensurability, strong fluctuations), and nonlinear regimes of microwave energy absorption, which are comparatively easy to achieve here because of the long relaxation times of the elementary excitations [8,9]. PACSOne member of this family of compounds that has practically escaped study is KTb(WO 4 ) 2 , which contains the rare-earth ion Tb 3+ ( 7 F 6 ) with an odd number of electrons.X-ray studies of the magnet KTb(WO 4 ) 2 have shown that this compound belongs to the monoclinic class C 2 /c with a chain structure [10]. There are 4 formulae units per elementary cell with cell parameters: a = 10.653 Å, b = = 10.402 Å, c = 7.573 Å, β = 130.76°. Crystal structure is represented in Fig. 1. The Tb ions form chains along [101] direction, distance between nearest Tb 3+ is 4.071 Å.The angular dependence of the magnetic susceptibility [10] shows that at low temperatures a purely Ising aniso-

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Field induced structural phase transition in layered compounds MR(MoO4)2 (M = K, Cs; R = Er, Tm)

Cited by 6 publications

References 4 publications

Magnetoelectric effect arising from a field-induced pseudo Jahn-Teller distortion in a rare-earth magnet

Magnetoelectric effect arising from a field-induced pseudo Jahn-Teller distortion in a rare-earth magnet

Neutron diffraction study on the two-dimensional Ising systemKEr(MoO4)2

Evidence for low-temperature antiferromagnetic phase transition in Ising singlet magnet KTb(WO4)2

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