Spin Ordering in Low-Dimensional Magnetic System Induced by Model Interaction
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ORIGINAL PAPER
Spin Ordering in Low-Dimensional Magnetic System Induced by Model Interaction S. Haldar1 · Ajay Kumar Ghosh1 Received: 27 April 2020 / Accepted: 5 June 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The magnetic susceptibility has been studied by using a new trial function for the model interaction between spins arranged in a low-dimensional square pyramidal system. We suggest that the exchange interaction depends on a power exponent which depends on the pyramidal structure in addition to the magnetic energy and thermal energy. We have calculated the magnetization as a function of the temperature and magnetic field keeping the exponent constant. Dependence of the susceptibility on a characteristic length related to the low-dimensional system exhibits novel features. Magnetic field dependence of the susceptibility has a maximum which shifts toward higher field as the temperature is increased. Even at higher fields, the susceptibility can be very small. The variations of the susceptibility with temperature exhibit maximum which depends on the external perturbing field. Keywords Spin ordering in nanosystems · Molecular magnet · Magnetic properties of superconductor
1 Introduction Low-dimensional spin systems and molecular magnets are of tremendous interest because of enriched magnetic properties relevant to applications of the magnetic systems. It is known that the spin susceptibility is governed by the pairing mechanism in superconducting systems [1]. A calculation of susceptibility and its dependence on the several variables such as magnetic field, system size, and form of the interaction has been carried out by several groups of researchers [2]. Sudden jump in magnetization with a field at lower temperature has been observed in molecular magnet [3]. Molecular magnet clusters can be used for low-temperature refrigeration which can attain the lowest achievable temperature [4]. Spin magnetism of a small system has been studied earlier [5]. Nanostructured spin systems are widely studied to understand the change in susceptibility in comparison with the bulk system. Identifying a unit of spin arrangement and the repetition of this unit is very crucial to understand the susceptibility of a bulk system. Susceptibility of a spin system exhibits Ajay Kumar Ghosh
[email protected] 1
Department of Physics, Jadavpur University, Kolkata 700032, India
reentrant behavior in small superconducting grains as a function of temperature [6]. Depending on the number of electrons, it is possible to observe the reentrant behavior. Switching field studies in nanocluster are found to be very sensitive to temperature [7]. Novel magnetic susceptibility in several superconducting and other systems is associated with the magnetic ordering in the octahedral structure [8–10]. Ferromagnetism and superconductivity are two mutually exclusive phenomena. But after the discovery of ruthenium-based cuprate samples, it has been observed that superconductivity and ferromagnetism can
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