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Concentrated spin-glass behavior in Al 37 Mn 30 <mml:…

1990; American Physical Society; Volume: 42; Issue: 4 Linguagem: Inglês

10.1103/physrevb.42.2337

1095-3795

Ratnamala Chatterjee, R. A. Dunlap, V. Srinivas, R. C. O’Handley,

Mineralogy and Gemology Studies

Detailed magnetic measurements on icosahedral ${\mathrm{Al}}_{37}$${\mathrm{Mn}}_{30}$${\mathrm{Si}}_{33}$ quasicrystals are presented. It has been established that this high-Mn-content quasicrystal is not a real ferromagnet and instead shows a concentrated spin-glass behavior with reentrant ferromagnetism. Low-field-magnetization measurements show a Brillouin-function-like behavior, suggesting a ${\mathit{T}}_{\mathit{c}}$ of 120 K. High-field M-T data approach Curie-like paramagnetism because of the large high-field susceptibility. Arott plots show that no spontaneous moment exists. Thermomagnetic hysteresis and time dependence are also observed in the magnetization. For the first time several magnetic quasicrystals with varying Mn and Si or Ge content can be located on the exchange-fluctuation axis of a magnetic phase diagram.