Andrieu S, Chatelain C, Lemine M, Berche B, Bauer P
Laboratoire de Physique des Matériaux, Université Henri Poincaré, Nancy 1, BP 239, F-54506 Vandoeuvre, France.
Phys Rev Lett. 2001 Apr 23;86(17):3883-6. doi: 10.1103/PhysRevLett.86.3883.
In ferromagnetic thin films, the Curie temperature variation with the thickness is always considered as continuous when the thickness is varied from n to n+1 atomic planes. We show that it is not the case for Fe in Fe/Ir superlattices. For an integer number of atomic planes, a unique magnetic transition is observed by susceptibility measurements, whereas two magnetic transitions are observed for fractional numbers of planes. This behavior is attributed to successive transitions of areas with n and n+1 atomic planes, for which the T(c)'s are not the same. Indeed, the magnetic correlation length is presumably shorter than the average size of the terraces. Monte Carlo simulations are performed to support this explanation.
在铁磁薄膜中，当厚度从n个原子平面变化到n + 1个原子平面时，居里温度随厚度的变化通常被认为是连续的。我们发现对于Fe/Ir超晶格中的铁并非如此。对于整数个原子平面，通过磁化率测量可观察到单一的磁转变，而对于分数个原子平面则观察到两个磁转变。这种行为归因于具有n个和n + 1个原子平面的区域的连续转变，其居里温度不同。实际上，磁关联长度可能比平台的平均尺寸短。进行了蒙特卡罗模拟以支持这一解释。
