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- Ginnarsson, K., et al.
(författare)
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Equilibrium and nonequilibrium magnetic behaviour of a reentrant Ising spin glass.
- 1992
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 104-107:3, s. 1607-1608
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Tidskriftsartikel (refereegranskat)abstract
- The reentrant Ising spin glass Fe0.62Mn0.38TiO3 has been investigated using SQUID magnetometry. The system is antiferromagnetic below TN(H = 0) = 33 K, and enters a mixed antiferromagnetic/spin glass phase below Tg(H = 0) = 25.8 K. Within the concept of a recent mean field model, a ratio TN(0)/Tg(0) close to unity indicates both intra- and interlayer frustration. The existence of an overlap length, lΔT, below which equilibrium spin correlations at temperatures T and T + ΔT are indistinguishable has been verified by magnetic relaxation experiments on this spin glass system
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| 2. |
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| 4. |
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| 5. |
- ANDERSSON, JO, et al.
(författare)
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OVERLAP LENGTH IN A CU-MN SPIN-GLASS PROBED BY AC SUSCEPTIBILITY
- 1993
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 48, s. 13977-13980
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Tidskriftsartikel (refereegranskat)abstract
- An important theoretical concept in the ‘’droplet” model of spin glasses is the existence of an overlap length. Experimentally this concept was verified by dc-magnetization measurements. However, recent ac-susceptibility measurements by Lefloch et al. [Europhys. Lett. 18, 647 (1992)] have been interpreted to contradict this result. In this paper, ac-susceptibility and dc-magnetization measurements on a Cu (2% Mn) spin glass are reported. The results of the ac-susceptibility measurements are consistent with dc measurements and provide evidence for the existence of an overlap length in 3d spin glasses at low temperatures.
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| 6. |
- BAJOREK, A, et al.
(författare)
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ON EXCHANGE MECHANISM IN HG1-XMNXS
- 1994
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 131, s. 363-368
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic susceptibility of Hg0.95Mn0.05S and Hg0.90Mn0.10S was measured by the SQUID technique. The experimental data were compared with the extended nearest neighbour pair approximation (ENNPA) calculation. The long range exchange interaction J = J(NN)R(-n), with the exponent n = 4, was found for both samples. The nearest neighbour exchange integral J(NN) was found to be around two times smaller than the effective exchange integral J(eff). The small value of the exponent n, which is a characteristic of the narrow gap semimagnetic semiconductors (SMSC’s), as well as the small J(NN)/J(eff) ratio, show the importance of a long-range exchange mechanism.
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| 7. |
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| 8. |
- DJURBERG, C, et al.
(författare)
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RELAXATION OF THE FIELD COOLED MAGNETIZATION IN 2D CU(MN) FILMS
- 1994
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 194, s. 303-304
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Tidskriftsartikel (refereegranskat)abstract
- The relaxation of the field cooled magnetisation of a multilayered 2D Cu(Mn) spin glass film has been investigated in a SQUID-magnetometer. The sample is cooled in a constant magnetic field (10 Oe) from a high temperature, where the magnetisation is at equilibrium, to a temperature below the freezing temperature, T(f). At constant temperature, the magnetisation is then found to increase with time at temperatures near T(f), showing an initial decrease followed by an increase at long time scales at intermediate temperatures and only decreases with time at lower temperatures. The behaviour, including the surprising downward relaxation away from the thermodynamic equilibrium magnetisation, is qualitatively interpreted in terms of a spin glass domain model.
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| 9. |
- DJURBERG, C, et al.
(författare)
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REMANENT MAGNETIZATION IN THE DILUTED ISING ANTIFERROMAGNET FE0.6ZN0.4F2
- 1994
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 75, s. 5541-5543
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Tidskriftsartikel (refereegranskat)abstract
- The field, H less-than-or-equal-to 5 T, and temperature, T greater-than-or-equal-to 2 K, dependence of the remanent magnetization mu of the diluted Ising antiferromagnet Fe0.6Zn0.4F2 has been investigated utilizing a superconducting quantum interference device magnetometer. The results at low temperatures, where there is no growth of random field domains after the field removal, are analyzed according to mu = AH(x)(T ln t/t0)-PSI + B, where the two terms are domain wall and volume contributions to the remanent magnetization, respectively. It is found that PSI decreases continuously with decreasing temperature, and reaches a value of almost-equal-to 0.15 at 3 K. The field exponent x is found to decrease with increasing temperature, attaining values between 2 and 3. The results show a more complex behavior of the low-temperature remanent magnetization than a model proposed by Nattermann and Vilfan which predicts constant values of the exponents: PSI almost-equal-to 0.4 and x almost-equal-to 2.
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