Magnetic and magnetocaloric properties of the exactly solvable mixed-spin Ising model on a decorated triangular lattice in a magnetic field

Abstract

The ground state, zero-temperature magnetization process, critical behaviour and isothermal entropy change of the mixed-spin Ising model on a decorated triangular lattice in a magnetic field are exactly studied after performing the generalized decorationiteration mapping transformation. It is shown that both the inverse and conventional magnetocaloric effect can be found near the absolute zero temperature. The former phenomenon can be found in a vicinity of the discontinuous phase transitions and their crossing, while the latter one occurs in some paramagnetic phases due to a spin frustration to be present at zero magnetic field. The inverse magnetocaloric effect can also be detected slightly above continuous phase transitions following the power-law dependence | − ∆S min iso | ∝ h n , where n depends basically on the ground-state spin ordering.

Magnetic properties and phase diagrams of mixed spin-1 and spin-1/2 Ising model on a checkerboard square structure: A Monte Carlo study

“…After the pioneering work of Onsager in solving the two dimensional Ising model analytically [15], many attempts to get an exact solution on different decorated systems such as triangular [16], honeycomb [17], kagome [18], bathroom-tile [19], and ruby [20] lattices have been obtained. Other lattices such as the checkerboard pattern is not an easy task to accomplish analytically.…”

Weak Singularities of the Isothermal Entropy Change as the Smoking Gun Evidence of Phase Transitions of Mixed-Spin Ising Model on a Decorated Square Lattice in Transverse Field

“…The derived exact analytical formulas ( 14)-( 17) allow a straightforward computation of the basic magnetocaloric properties as, for instance, the isothermal entropy change or the adiabatic temperature change. The isothermal entropy change can be calculated as a difference of the entropy at nonzero and zero magnetic fields ∆S iso = S d (T, Ω = 0) − S d (T, Ω = 0) at the constant temperature, while the adiabatic change of temperature can be traced back from contour lines of the density plot of the entropy (14) in the fieldtemperature plane.…”

“…Among these paradigmatic examples, one could for instance mention Fisher's superexchange antiferromagnet, which refers to a spin-1/2 Ising model on a decorated square lattice with spatially modulated ferromagnetic and antiferromagnetic interactions in a longitudinal magnetic field [7,8]. Exact solutions for several variants and extensions of the original Fisher's superexchange model have been found by considering higher spin values, crystal-field anisotropy or different lattice geometries [9][10][11][12][13][14]. A few additional special cases of 2D Ising models partially taking into consideration the longitudinal magnetic field were exactly solved by making use of a precise mapping correspondence with free-fermion 16-vertex or 32-vertex models [15][16][17][18][19][20][21].…”

Tomonaga–Luttinger Spin Liquid and Kosterlitz–Thouless Transition in the Spin-1/2 Branched Chains: The Study of Topological Phase Transition

“…The magnetization of 1-D Heisenberg chain models reveals fascinating features such as an intermediate plateau [17,18,[26][27][28][29][30][31][32][33][34][35][36], jumps and steps [37][38][39][40], and spin liquid states [24,25,41,42]. In recent works, the ground-state phase diagram and the low-temperature magnetization process of several spin-1/2 Heisenberg branched chains have been examined, whose magnetic structure is inspired by the heterobimetallic coordination polymers [43,44].…”