Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes: Green's function approach

Mi, Bin-Zhou; Zhai, Lu; Hua, Lingling

doi:10.1016/j.jmmm.2015.09.016

Cited by 9 publications

(4 citation statements)

References 54 publications

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“…Apart from these, analytical calculations based on continuum approximations 10,11,[33][34][35][36][37] have also succeeded in describing the main phenomenology. Other theoretical methods 38,39 or simulation techniques [40][41][42][43] have also partially addressed these issues.…”

Section: Introductionmentioning

confidence: 99%

Tailoring dual reversal modes by helicity control in ferromagnetic nanotubes

2020

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We investigate the effects of the competition between exchange (J) and dipolar (D) interactions on the magnetization reversal mechanisms of ferromagnetic nanotubes. Using first atomistic Monte Carlo (MC) simulations for a model with Heisenberg spins on a cylindrical surface, we compute hysteresis loops for a wide range of the γ = D/J parameter, characterizing the reversal behavior in terms of the cylindrical magnetization components and the vorticity parameter along the tube length. For γ's close to the value for which helical (H) states are stable at zero applied field, we show that the hysteresis loops can occur in four different classes that are combinations of two reversal modes with well-differentiated coercivities with probabilities that depend on the tube length and radius. This variety in the reversal modes is found to be linked to the metastability of the H states during the reversal that induce different paths followed along the energy landscape as the field is changed. We further demonstrate that reversal by either of the two modes can be induced by tailoring the nanotube initial state so that vortices with equal or contrary chirality are formed at the ends, thus achieving low or high coercive fields at will without changing γ. Finally, the results of additional micromagnetic simulations performed on tubes with similar aspect ratio show that dual switching modes and its tailoring can also be observed in tubes with more microscopic dimensions. arXiv:1904.05116v1 [cond-mat.mtrl-sci]

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Section: Introductionmentioning

confidence: 99%

Tailoring dual reversal modes by helicity control in ferromagnetic nanotubes

2020

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“…However, since their magnetization is close to zero, standard magnetic characterization precluded their experimental evidence until the advent of more sensitive techniques allowed their observation in individual nanocylinders, nanotubes and dot-shaped elements of different compositions by means of electron holography 35,36 , cantilever-based torque magnetometry [37][38][39][40] , nanoscale torque-SQUID magnetometry 41 , spin-polarized scanning tunneling spectroscopy 42 , X-ray microscopy 43 and MFM 44 . Different theoretical and simulation approaches have been used in order to study the thermodynamic properties of magnetic hollow nanocylinders, including micromagnetic studies 15,45 , scaling techniques 46,47 , many-body Green's functions [48][49][50] , ab-initio calculations [51][52][53] , and Monte Carlo (MC) simulations 54 .…”

Section: Introductionmentioning

confidence: 99%

“…Different theoretical and simulation approaches have been used in order to study the thermodynamic properties of magnetic hollow nanocylinders, including micromagnetic studies 15,45 , scaling techniques 46,47 , many-body Green's functions [48][49][50] , ab-initio calculations [51][52][53] , and Monte Carlo (MC) simulations 54 .…”

Section: Introductionmentioning

confidence: 99%

Change in the magnetic configurations of tubular nanostructures by tuning dipolar interactions

Salinas

Restrepo

Iglesias

2018

Sci Rep

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We have investigated the equilibrium states of ferromagnetic single wall nanotubes by means of atomistic Monte Carlo simulations of a zig-zag lattice of Heisenberg spins on the surface of a cylinder. The main focus of our study is to determine how the competition between short-range exchange (J) and long-range dipolar (D) interactions influences the low temperature magnetic order of the nanotubes as well as the thermal-driven transitions involved. Apart from the uniform and vortex states occurring for dominant J or D, we find that helical states become stable for a range of intermediate values of γ = D/J that depends on the radius and length of the nanotube. Introducing a vorticity order parameter to better characterize helical and vortex states, we find the pseudo-critical temperatures for the transitions between these states and we establish the magnetic phase diagrams of their stability regions as a function of the nanotube aspect ratio. Comparison of the energy of the states obtained by simulation with those of simpler theoretical structures that interpolate continuously between them, reveals a high degree of metastability of the helical structures that might be relevant for their reversal modes.

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“…The relevance of these systems relays on their ability of changing their magnetic properties just by the change of one compound for another, creating the enticingly possibility of designing materials 'a la carte'. These compounds have many potential applications in the area of thermomagnetic and magneto-optical recording, as well as been an ideal source to study a variety of critical phenomena [3][4][5]. Despite their relative simplicity, mixed spin Ising models have proven to be very useful to study the magnetic and critical properties of these materials [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Mixed spin-1 and spin-2 Ising model: study of the ground states

2018

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We calculate ground state configurations of a mixed Ising model on a square lattice where spins =   S 2, 1, 0 i A in one A sublattice are in alternating sites with spins s = 1, 0 j B , located on the other B sublattice.The Hamiltonian of the system includes nearest-neighbors interactions between the S i A and s j B spins, next-nearest-neighbors interactions between the S i A spins, and between the s j B spins, single-ion anisotropy, and an external magnetic field. [24-27], and Fe Fe II III bimetallic oxalates, present ferrimagnetic ordering and compensation temperatures, properties that OPEN ACCESS RECEIVED

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Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes: Green's function approach

Cited by 9 publications

References 54 publications

Tailoring dual reversal modes by helicity control in ferromagnetic nanotubes

Tailoring dual reversal modes by helicity control in ferromagnetic nanotubes

Change in the magnetic configurations of tubular nanostructures by tuning dipolar interactions

Mixed spin-1 and spin-2 Ising model: study of the ground states

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