Anisotropy of the critical magnetic susceptibility of gadolinium

Geldart, D. J. W.; Hargraves, P.; Fujiki, N. M.; Dunlap, R. N. A.

doi:10.1103/physrevlett.62.2728

Cited by 58 publications

(24 citation statements)

References 29 publications

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“…Curvature indicates deviations from these laws. Symbols show measurements of two glass-forming liquids [56] and two ferromagnetic materials [40][41][42]50,51], as given in the legend. Solid lines are from the mean-field cluster model.…”

Section: Nanocanonical Ensemble Equilibrium Landau Theory and Mean-mentioning

confidence: 99%

The Big World of Nanothermodynamics

Chamberlin

2014

Entropy

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Nanothermodynamics extends standard thermodynamics to facilitate finite-size effects on the scale of nanometers. A key ingredient is Hill's subdivision potential that accommodates the non-extensive energy of independent small systems, similar to how Gibbs' chemical potential accommodates distinct particles. Nanothermodynamics is essential for characterizing the thermal equilibrium distribution of independently relaxing regions inside bulk samples, as is found for the primary response of most materials using various experimental techniques. The subdivision potential ensures strict adherence to the laws of thermodynamics: total energy is conserved by including an instantaneous contribution from the entropy of local configurations, and total entropy remains maximized by coupling to a thermal bath. A unique feature of nanothermodynamics is the completely-open nanocanonical ensemble. Another feature is that particles within each region become statistically indistinguishable, which avoids non-extensive entropy, and mimics quantum-mechanical behavior. Applied to mean-field theory, nanothermodynamics gives a heterogeneous distribution of regions that yields stretched-exponential relaxation and super-Arrhenius activation. Applied to Monte Carlo simulations, there is a nonlinear correction to Boltzmann's factor that improves agreement between the Ising model and measured non-classical critical scaling in magnetic materials. Nanothermodynamics also provides a fundamental mechanism for the 1/f noise found in many materials.

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Section: Nanocanonical Ensemble Equilibrium Landau Theory and Mean-mentioning

confidence: 99%

The Big World of Nanothermodynamics

Chamberlin

2014

Entropy

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“…Magnetic anisotropies are also temperature-dependent [179,180], which vanish at T c in particular for itinerant ferromagnets expect for Gd, of which the finite anisotropies may be present at T > T c [181]. The different size-and temperature-dependences of surface, volume and shape anisotropies may give rise to the spin reorientation transition (SRT) at the corresponding temperature T r (D).…”

Section: When Films Have the Same Two Surfaces Or Interfaces Eq (46mentioning

confidence: 99%

Size Dependence of Structures and Properties of Magnetic Materials

Jiang¹,

Lang²

2007

TONANOJ

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Due to the involvement of high portion of atomic coordination imperfection in surfaces and interfaces, the properties of magnetic nanocrystals dramatically differ from that of the corresponding bulk counterparts, which have led to a surge in both experimental and theoretical investigations in the past decades. This review summarizes the studies for these size-dependent magnetic properties, and additional thermal or phase stabilities, and mechanical properties. To interpret the above phenomena, a thermodynamic model for the size dependence and interface dependences of these properties is described, which is based on Lindemann s criterion for melting, Mott s expression for the vibrational melting entropy, and Shi s model for the size-dependent melting temperature. The model without any adjustable parameter is confirmed by a large number of experimental results, and helps us to understand the structures and properties of the magnetic nanocrystals. Moreover, other theoretical works on the above properties are also mentioned and commented.

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“…As the only simple ferromagnet among the rare earth elements at room temperature, the metal gadolinium (Gd) has been broadly investigated in past decades (Geldart et al 1962;Legvold 1980;Gschneidner and Pecharsky 2000;Dan'kov et al 1998) and has drawn tremendous attention, particularly with respect to the finite-temperature magnetic properties and magnetocaloric effect. It is well known that Gd crystallizes in the hexagonal close-packed structure with a lattice constant of a = 3.629 Å , c/a = 1.579.…”

Section: Introductionmentioning

confidence: 99%

Magnetic entropy change in bulk nanocrystalline Gd metals

et al. 2011

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The magnetocaloric properties of the asconsolidated nanocrystalline and coarse-grained gadolinium metals were studied in the present work. With the decrease of Gd grains from micrometer to nanometer range, magnetic entropy change drops surprising from 10.07 to 4.47 J kg -1 K -1 at a magnetic-field change of 5 T, and their resultant magnetic entropy change uniformly peaks at 294, 290, and 288 K, respectively, corresponding to the magnetic transition temperature of the three samples. The Curie temperature T C of the nanocrystalline Gd shifts by more than 6 K below that of coarse-grained Gd sample. However, the values of magnetic entropy change of the nanocrystalline metals exhibit a more constant tendency compared with the coarse-grained sample. The Arrott plots indicate the second-order character of magnetic phase transition still in the nanocrystalline Gd metals. The refrigerant capacity calculated is also used to evaluate material refrigeration capacity.

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Anisotropy of the critical magnetic susceptibility of gadolinium

Cited by 58 publications

References 29 publications

The Big World of Nanothermodynamics

The Big World of Nanothermodynamics

Size Dependence of Structures and Properties of Magnetic Materials

Magnetic entropy change in bulk nanocrystalline Gd metals

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