Universal fluctuations in orbital diamagnetism

Pramana: Journal of physics

ARNAB SAHA^3¹  P S PAL^1,2²  A M JAYANNAVAR^1,2³ 

[1] Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400 085, India^2;Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005, India^1;Savitribai Phule Pune University, Ganeshkhind, Pune 411 007, India^3

关键词: Diamagnetism;    fluctuation;    magnetic field;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

Bohr–van Leuween theorem has attracted the notice of physicists for more than 100 years. The theorem states about the absence of magnetisation in classical systems in thermal equilibrium. In this paper, we discuss about fluctuations of magnetic moment in classical systems. In recent years, this topic has been investigated intensivelyand it is not free from controversy.We have considered a system consisting of a single particle moving in a plane. A magnetic field is applied perpendicular to the plane. The system is in contact with a thermal bath.We have considered three cases: (a) particle moving in a homogeneous medium, (b) particle moving in a medium with space-dependent friction and (c) particle moving in a medium with space-dependent temperature. For all the three cases, the averagemagnetic moment and fluctuations in magnetic moment have been calculated. Average magnetic moment saturates to a finite value in the case of free particle but goes to zero when the particle is confined by a 2D harmonic potential. Fluctuations in magnetic moment shows universal features in the presence of arbitrary friction inhomogeneity. For this case, the system reaches equilibrium asymptotically. In the case of space-dependent temperature profile, the stationary distribution is non-Gibbsian and fluctuations deviate from universal value for the bounded system only.

【 授权许可】

CC BY