Magnetic and electrical properties of ferromagnetic alloys near the critical concentration

The Royal Society - Tập 306 Số 1486 - Trang 355-368 - 1968
J. Mathon1
1Department of Mathematics, Imperial College, London, England

Tóm tắt

A simple molecular field theory is developed to explain at least qualitatively the behaviour of weakly ferromagnetic and strongly paramagnetic alloys near their critical concentration c F . The free energy of a weakly ferromagnetic alloy can be expanded in powers of magnetization ζ and a modified Landau theory is used to calculate the concentration dependence of the magnetization, specific heat and the susceptibility near c F . It is believed that such a theory can work better in this case than does the usual Landau theory as fluctuations in ζ are relatively small for low temperatures. A change in low temperature resistivity around c F is also expected as a result of ciritcal scattering of conduction electrons. This change was first calculated by Rice (1967) for strongly paramagnetic alloys giving a large T 2 term. However, this calculation is not applicable for c very close to c F . It is shown that for c → c F the paramagnetic resistivity remains finite and has a maximum for c ═ c F , ρ Para c ═ c F ∝ T 5/3 . It is also found that the ferromagnetic resistivity ρ ferro has a similar dependence on concentration and temperature as ρ Para and ρ ferro c ═ c F ═ ρ Para c ═ c F , i.e. the resisitivity is symmetrical around c F .

Từ khóa


Tài liệu tham khảo

10.1103/PhysRev.169.417

10.1103/PhysRevLett.18.1125

10.1103/PhysRevLett.17.750

Doniach S. Engelsberg S. & Rice M. J . 1966 Proc. 10 In t. Conf. Low Temp. Phys. Moscow.

Edwards D. M., 1968, Proc. Roy, Soc. A, 303, 127

Foner S., 1967, Bull. A m, Phys. Soc., 12, 311

Herring C. 1966 M agnetism vol. 4. New Y ork : Academic Press.

Izuyam, 1963, J, Phys. Soc. Japan, 18, 1025

10.1103/RevModPhys.39.395

Landau L. D. & Lifshitz E . M. 1958 Statist. Phys. ch. 14. London: Pergam on Press.

1968, Proc. Roy, Soc. A, 302, 409

10.1016/0022-3697(66)90111-9

10.1103/PhysRev.159.153

10.1103/PhysRev.164.759

10.1088/0370-1328/83/1/309

10.1016/0031-9163(65)91291-6

1968, J . A ppl, Phys., 39, 1061

Ziman J . M. i960 Electrons and phonons ch. 7. Oxford: Clarendon Press.

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Thông tin xuất bản

The Royal Society

Tập 306 Số 1486

355-368

Thông tin tác giả