Magnetoelastic behaviour and the spin-reorientation transition in HoAl<sub>2</sub>

Ibarra, M. R.; Može, O.; Algarabel, P. A.; Arnaudas, J.I.; Abell, J.S.; Moral, A. del

doi:10.1088/0022-3719/21/14/013

Cited by 18 publications

(12 citation statements)

References 21 publications

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“…Figure 9 shows the comparison between the theoretical normalized results, ͕−⌬S mag ͖ and ͕−⌬ mag ͖, for ⌬H =5 T as a function of temperature for the RAl 2 ͑R = Pr, Nd, Tb, Dy, Ho, and Er͒ compounds. As noted above, for HoAl 2 , due to the spin reorientation transition, 11,12 the calculations are shown for the temperatures above it ͑T SR ϳ 20 K͒.…”

Section: Comparison Between Normalized Experimental and Calculated −⌬mentioning

confidence: 89%

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Magnetoresistivity as a probe to the field-induced change of magnetic entropy inRAl2compounds(R=Pr,
Campoy
¹
,
Plaza
²
,
Coelho
³

et al. 2006
Phys. Rev. B

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The heat capacity C P ͑T͒ of the ferromagnetic compounds RAl 2 ͑R =Pr,Nd,Tb,Dy,Ho,Er͒ was measured at zero and applied magnetic field of 5 T in the temperature interval from 2 to 200 K. From these results are calculated the magnetic component of the entropy change, −⌬S mag ͑T͒ = S͑0,T͒ − S͑H , T͒. From resistivity measurements, ͑H , T͒, from 2 to 300 K in the same compounds, we calculated the resistivity change due to the applied magnetic field, −⌬ mag ͑T͒ = ͓ mag ͑0,T͒ − mag ͑H , T͔͒. The results are compared and we observed a similar dependence between −⌬ mag ͑T͒ and ͑T / T C ͒ m ⌬S mag ͑T͒ with m = 0 for T ജ T C and m = 1 for T ഛ T C. A simple model using a Hamiltonian considering molecular and crystalline electric fields, in a mean field approximation, is adopted for the calculus. Our results show that theory and experiment are in good agreement showing that the magnetoresistivity is a probe to the field-induced change of magnetic entropy in these compounds and can be extended to other materials. A model for the factor connecting both quantities, −⌬S mag ͑T͒ and −⌬ mag ͑T͒, is developed. This factor contains mainly the effective exchange integral which is related to Fermi energy that in turn is related to the electron effective mass.

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Section: Comparison Between Normalized Experimental and Calculated −⌬mentioning

confidence: 89%

“…At this temperature a spin reorientation transition occurs changing the easy magnetization direction from the ͓100͔ direction above T SR , to ͓110͔ below T SR . 11,12 In Fig. 2 we show the C P ͑H , T͒ curves obtained for zero and for 5 T applied magnetic field for the DyAl 2 compound.…”

Section: Heat Capacity C P "H T…mentioning

confidence: 99%

Magnetoresistivity as a probe to the field-induced change of magnetic entropy inRAl2compounds(R=Pr,
Campoy
¹
,
Plaza
²
,
Coelho
³

et al. 2006
Phys. Rev. B

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“…The only exception is HoAl 2 , which exhibits an orthorhombic distortion upon spin reorientation transition that occurs in the ferromagnetic state [20]. On the other hand, several of the mixed heavy lanthanide dialuminides exhibit first order like anomalies at low temperature without apparent structural distortions [21].…”

Section: Materials With Structural Transformations or Distortions Coumentioning

confidence: 99%

Anomalous Schottky Specific Heat and Structural Distortion in FerromagneticPrAl2

et al. 2013

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Unique from other rare earth dialuminides, PrAl(2) undergoes a cubic to tetragonal distortion below T = 30 K in a zero magnetic field, but the system recovers its cubic symmetry upon the application of an external magnetic field of 10 kOe via a lifting of the 4f crystal field splitting. The nuclear Schottky specific heat in PrAl(2) is anomalously high compared to that of pure Pr metal. First principles calculations reveal that the 4f crystal field splitting in the tetragonally distorted phase of PrAl(2) underpins the observed unusual low temperature phenomena.

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“…For example, HoAl 2 undergoes a first-order spin-reorientation transition in the ferromagnetic state, which is not observed in any other member of the RAl 2 series. 5,9 Spin-reorientation transition also exists in DyAl 2 , even though it is no longer a first-order transformation. 10 The 4f charge densities of the rare-earth atoms that are represented by the second-order Stevens's factors are significantly different.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical study of the magnetic and structural properties ofEr0.75Tb0.25Al2

et al. 2010

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The Er 0.75 Tb 0.25 Al 2 alloy has been investigated by x-ray powder diffraction, magnetization, and ac magneticsusceptibility measurements. The low-field magnetization measured as a function of temperature indicates a ferromagnetic transition at ϳ36 K and another transition with thermal hysteresis at ϳ18 K. The ac magneticsusceptibility measurements show frequency dependence below the ferromagnetic transition temperature, T C . Low-temperature x-ray powder-diffraction measurements suggest that although no structural transformation occurs around 18 K, a steplike anomaly in the lattice parameters does exist in the vicinity of the transition. First-principles electronic-structure calculations show anomalous density of states at the Fermi level. The results are comparable with the previously reported Er 0.75 Dy 0.25 Al 2 alloy, thus supporting an earlier assumption that mixing two rare-earth ions with opposite signs of second-order Steven's factor in RAl 2 alloys creates a competition between the magnetoelastic and quadrupolar interactions, giving rise to multiple magnetic ordering phenomena.

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Magnetoelastic behaviour and the spin-reorientation transition in HoAl₂

Cited by 18 publications

References 21 publications

Magnetoresistivity as a probe to the field-induced change of magnetic entropy inRAl2compounds(R=Pr,
Campoy
¹
,
Plaza
²
,
Coelho
³

et al. 2006
Phys. Rev. B

Magnetoresistivity as a probe to the field-induced change of magnetic entropy inRAl2compounds(R=Pr,
Campoy
¹
,
Plaza
²
,
Coelho
³

et al. 2006
Phys. Rev. B

Anomalous Schottky Specific Heat and Structural Distortion in FerromagneticPrAl2

Experimental and theoretical study of the magnetic and structural properties ofEr0.75Tb0.25Al2

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Magnetoelastic behaviour and the spin-reorientation transition in HoAl2

Cited by 18 publications

References 21 publications

Magnetoresistivity as a probe to the field-induced change of magnetic entropy inRAl2compounds(R=Pr,Campoy1, Plaza2, Coelho3 et al. 2006Phys. Rev. B

Magnetoresistivity as a probe to the field-induced change of magnetic entropy inRAl2compounds(R=Pr,Campoy1, Plaza2, Coelho3 et al. 2006Phys. Rev. B

Anomalous Schottky Specific Heat and Structural Distortion in FerromagneticPrAl2

Experimental and theoretical study of the magnetic and structural properties ofEr0.75Tb0.25Al2

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Product

Resources

About

Magnetoelastic behaviour and the spin-reorientation transition in HoAl₂

Magnetoresistivity as a probe to the field-induced change of magnetic entropy inRAl2compounds(R=Pr,
Campoy
¹
,
Plaza
²
,
Coelho
³

et al. 2006
Phys. Rev. B

Magnetoresistivity as a probe to the field-induced change of magnetic entropy inRAl2compounds(R=Pr,
Campoy
¹
,
Plaza
²
,
Coelho
³

et al. 2006
Phys. Rev. B