The effect of a crystalline electric field on the magnetic transition temperatures of rare-earth rhodium borides

doi:10.1016/0375-9601(82)90258-4

Physics Letters A

Volume 91, Issue 1, 16 August 1982, Pages 35-36

https://doi.org/10.1016/0375-9601(82)90258-4 Get rights and content

Abstract

A simple molecular field model is presented for the prediction of magnetic transition temperatures of rare-earth (RE) compounds when crystalline electric field (CEF) splittings are significant. The model is applied to the RERh₄B₄ (RE=Gd−Tm) series, using what is known about the crystal field in these materials.

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Cited by (143)

Single crystal growths and magnetic properties of hexagonal polar semimetals RAuGe (R = Y, Gd–Tm, and Lu)
2023, Journal of Alloys and Compounds
We study structural and magnetic properties of rare-earth based semimetals RAuGe (R = Y, Gd–Tm, and Lu) using flux-grown single crystals. These compounds belong to the space group P6₃mc, which is associated with the noncentrosymmetric polar point group 6mm. We confirm the systematic structural evolution at room temperature as a function of ionic radius of rare earths to clarify the isopointal crossover between two polar structures: three-dimensional LiGaGe-type and quasi-two-dimensional NdPtSb-type. Magnetism shows a characteristic anisotropy in reasonable agreement with the crystal electric field (CEF) theory; the easy-plane-type anisotropy for R = Tb and Dy turns into the Ising-type anisotropy for R = Er and Tm. We evaluate the CEF parameters based on the Stevens operators to reasonably reproduce the temperature dependence of magnetic susceptibilities and specific heat for RAuGe (R = Tb–Tm). The estimated energy scale of the Ising gap (∼ 11 meV) in TmAuGe is consistent with an excitation observed in an inelastic neutron scattering experiment. These findings suggest an opportunity for interplay between conduction electrons and nontrivial spin structures in the family of magnetic polar semimetals RAuGe.
Complex magnetic ordering in RE<inf>5</inf>Pd<inf>2</inf>In<inf>4</inf> (RE = Tb-Tm) compounds investigated by neutron diffraction and magnetometric measurements
2021, Journal of Alloys and Compounds
The RE₅Pd₂In₄ (RE = Tb-Tm) compounds crystallize with the orthorhombic Lu₅Ni₂In₄-type crystal structure (Pbam space group). In this work we report results of structural and magnetic studies by means of X-ray and neutron diffraction as well as dc and ac magnetometric data. Magnetic susceptibility and neutron diffraction data revealed rare-earth moments order at low temperatures with complex magnetic structures showing a cascade of temperature-induced transitions. The magnetic ordering temperatures are found to be 97, 88, 28.5, 16.5 and 4.3 K for RE = Tb, Dy, Ho, Er and Tm, respectively. Magnetic structures related to the propagation vector ${\vec{k}}_{1} = [0, 0, 0]$ are found just below the magnetic ordering temperatures in majority of the investigated compounds (RE = Tb-Er). Below the Curie temperature T_C they have purely ferromagnetic character in Tb₅Pd₂In₄ and Dy₅Pd₂In₄. A ferrimagnetic order finally sets at lower temperatures in Dy₅Pd₂In₄, while in Ho₅Pd₂In₄ two magnetic phases related to ${\vec{k}}_{1}$ are observed: the antiferromagnetic one (phase I) and the ferrimagnetic one (phase II, coexisting with phase I at lower temperatures). Er₅Pd₂In₄ is a canted antiferromagnet with additional ferromagnetic component developing at lower temperatures. A purely antiferromagnetic component of magnetic structure with enlarged magnetic unit cell appears with decreasing temperature in Tb₅Pd₂In₄ ( ${\vec{k}}_{2} = [0, \frac{1}{2}, 0]$ and ${\vec{k}}_{3} = [0, \frac{1}{2}, \frac{1}{2}]$ ) while in Ho₅Pd₂In₄ such component ( ${\vec{k}}_{4} = [\frac{1}{4}, 0, 0]$ ) is present within whole temperature range below the magnetic ordering temperature. Magnetic structure of Tm₅Pd₂In₄, exceptionally, has no ${\vec{k}}_{1}$ component, but is an antiferromagnetic incommensurate one related to two propagation vectors: ${\vec{k}}_{5} = [0.073 (3), 0.451 (1), \frac{1}{2}]$ and ${\vec{k}}_{6} = [0, 0.335 (2), \frac{1}{2}]$ . In majority of the compounds (RE = Tb-Er) the first rare-earth 4g site (noted as 4g1) orders at lower temperature than two remaining sites (2a and 4g2). The direction of the magnetic moments depends on rare-earth element involved and indicates an influence of single-ion anisotropy in the crystalline electric field (CEF).
Crystal structure and magnetic properties of R<inf>11</inf>Co<inf>4</inf>In<inf>9</inf> (R=Tb, Dy, Ho and Er) compounds
2021, Intermetallics
Citation Excerpt :
The theoretical dependence is almost fulfilled for the paramagnetic Curie temperatures while for the critical temperatures of magnetic ordering (TC,N) a large discrepancy between the experimental and calculated temperatures is observed, especially visible for R = Tb and Dy. Such a result indicates a strong influence of crystalline electric field (CEF) on stability of the magnetic order [27]. Similar discrepancies have been observed in R2CoIn8 [17] and R2CoGa8 [28] (R = rare earth element).
Crystal structure and magnetic properties of the R₁₁Co₄In₉ compounds (R = Tb–Er) have been investigated by means of X-ray diffraction as well as dc magnetic measurements. The compounds crystallize in the orthorhombic Nd₁₁Pd₄In₉-type crystal structure (Cmmm space group) in which the rare earth atoms occupy five nonequivalent sublattices. Magnetic properties of the investigated compounds are related mainly to the R³⁺ ions. The values of effective magnetic moments in the paramagnetic state are close to the free R³⁺ ion values while the moments in the ordered state at T = 2.0 K (R = Tb, Dy) or T = 1.9 K (R = Ho, Er) and H = 90 kOe are lower than the respective R³⁺ moments. The compounds show complex magnetic properties below 95 K (Tb), 88 K (Dy), 35 K (Ho) and 5.4 K (Er). With increase of temperature the antiferromagnetic ground state changes to the ferro- or ferrimagnetic one. The critical temperatures of magnetic ordering do not fulfill the de Gennes scaling indicating a strong influence of the crystal electric field (CEF) in stabilizing the magnetic order.
Magnetic properties and magnetic structures of R<inf>2</inf>PdGe<inf>6</inf> (R = Pr, Nd, Gd-Er) and R<inf>2</inf>PtGe<inf>6</inf> (R = Tb, Ho, Er)
2020, Journal of Magnetism and Magnetic Materials
Polycrystalline samples of the intermetallic compounds R₂PdGe₆ (R = Pr, Nd, Gd-Er) and R₂PtGe₆ (R = Tb, Ho, Er) have been studied using X-ray diffraction as well as magnetometric and neutron diffraction measurements. All compounds have an orthorhombic crystal structure of the Yb₂PdGe₆-type (space group Cmca) and are antiferromagnetic with the Néel temperatures ranging from 4.9 K for Er₂PtGe₆ up to 48 K for Tb₂PdGe₆. The magnetic properties and specific heat data collected for Nd₂PdGe₆ show the presence of an additional phase transition below T_N at T = 4 K. Based on the neutron diffraction data, the magnetic structures have been determined for R₂PdGe₆ (R = Pr, Nd, Tb, Dy, Ho) and R₂PtGe₆ (R = Tb and Er). Both the magnetic properties and neutron diffraction data indicate that the magnetic moment is localized on rare earth atoms. The magnetic unit cell is equal to the crystal one, however, individual compounds show different types of magnetic orderings. Magnetic moments in Pr₂PdGe₆ form a non-collinear antiferromagnetic structure at low temperatures with magnetic moments confined to the (0 0 1) plane. The low temperature magnetic structure in Nd₂PdGe₆ is a collinear antiferromagnetic one with moments parallel to the b-axis and coupled ferromagnetically within the (0 0 1) plane, while along the c-axis the moments follow the + − − + sequence. With increasing temperature, a transition to a modulated magnetic structure is observed in Nd₂PdGe₆ at T = 4 K. The magnetic moments in R₂PdGe₆ (R = Tb, Dy, Ho) and Tb₂PtGe₆ assume a non-collinear antiferromagnetic order within the (0 0 1) plane with the + − + − sequence of signs of the moments in the neighboring planes along the c-axis. The Er moments in Er₂PtGe₆ form a collinear magnetic structure with magnetic moments oriented along the a-axis and coupled ferromagnetically within the (0 0 1) plane. Along the c-axis the moments follow the + − + − sequence. The magnetic structures determined here are discussed on the basis of the competition between the RKKY-type interactions and influence of Crystalline Electric Field.
Crystal structure and complex magnetic properties of R<inf>11</inf>Pd<inf>4</inf>In<inf>9</inf> compounds (R = Y, Gd–Er)
2020, Intermetallics
Citation Excerpt :
The straight lines indicate theoretical dependence, predicted by the RKKY theory, with Gd-based compounds taken as reference owing to the fact that the Gd3+ ion is in the S-state with zero orbital momentum and thus is not influenced by the crystalline electric field. The observed large discrepancy between the experimental and calculated temperatures, especially visible in TC for R = Tb and Dy, indicates strong influence of the crystalline electric field (CEF) on stability of the magnetic order in both series of compounds [14]. Similar discrepancies, attributed to the influence of CEF, have been observed in RRh4B4 [15] and R2CoGa8 (R = rare earth element) [16].
Magnetic properties of the R₁₁Pd₄In₉ compounds (R = Y, Gd–Er) were investigated by means of X-ray diffraction and magnetic measurements. Three of these compounds, namely those with R = Y, Ho and Er, are newly synthesized. The compounds crystallize in the orthorhombic Nd₁₁Pd₄In₉-type crystal structure (oC48, Cmmm) in which the rare earth atoms occupy five nonequivalent sublattices. Magnetic properties of the investigated compounds are related mainly to the R³⁺ ions, except the case of Y₁₁Pd₄In₉ which is a Pauli paramagnet. For R = Gd-Er, the values of effective magnetic moments in the paramagnetic state are close to the free R³⁺ ion values while the moments in the ordered state at T = 2 K and H = 90 kOe are lower than the respective R³⁺ moments. The compounds have complex magnetic properties. All paramagnetic Curie temperatures are positive suggesting that the ferromagnetic interactions are predominant. However, the low temperature data indicate an antiferromagnetic order. With increase of temperature the magnetic properties change from antiferro-to ferrimagnetic and finally to paramagnetic ones. The critical temperatures of magnetic ordering do not fulfill the de Gennes scaling, indicating a crystalline electric field contribution to stabilization of the magnetic order at low temperatures. The neutron diffraction measurements, performed for Ho₁₁Pd₄In₉, reveal a coexistence of two magnetic phases at low temperatures: the antiferromagnetic with propagation vector k = [0,0,½] and the ferrimagnetic one with k = [0,0,0]. The antiferromagnetic order is predominant at low temperatures while the ferrimagnetic one dominates at intermediate temperatures.
Magnetic properties and magnetic structures of R<inf>2</inf>TGe<inf>6</inf> (T = Ni, Cu; R = Tb, Ho and Er)
2019, Journal of Alloys and Compounds
The magnetic properties and magnetic structures of the R₂TGe₆ compounds (T = Ni and Cu, R = Tb, Ho and Er) were studied by magnetometric and neutron diffraction measurements. All compounds have an orthorhombic crystal structure of the Ce₂CuGe₆-type and are antiferromagnetic with the Néel temperatures ranging from 6 K for Er₂CuGe₆ up to 42 K for Tb₂NiGe₆. Based on the neutron diffraction data the magnetic structures were determined for R₂NiGe₆ (R = Tb, Er) and R₂CuGe₆ (R = Ho, Er). In these compounds the magnetic moments localized on the rare earth element form a collinear commensurate magnetic structure. The magnetic unit cell is equal to the crystal one in R₂NiGe₆ (R = Tb, Er) while it is doubled along the a-axis (propagation vector k = (½, 0, 0)) in R₂CuGe₆ (R = Ho and Er). The obtained magnetic structures are discussed on the basis of competition between the RKKY-type interactions and influence of Crystalline Electric Field (CEF).

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^☆: Work supported by the U.S. Department of Energy.

¹: Also at Physics Dept., University of Chicago.

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The effect of a crystalline electric field on the magnetic transition temperatures of rare-earth rhodium borides☆

Abstract

Solid State Phys.

J. Magn. Magn. Mater.

J. Appl. Phys.

Susceptibility and Mössbauer studies of magnetic rare earth-iron-silicides

J. Phys. Soc. Japan