Dielectric Modulation of Two-Dimensional Dipolar Materials

Wang, Ziwei; Luijten, Erik

doi:10.1103/physrevlett.123.096101

Cited by 12 publications

(8 citation statements)

References 44 publications

(63 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In recent years, two-dimensional arrays of magnetic nanoparticles (MNPs) have received significant attention due to their unique magnetic properties and potential technological applications [1][2][3][4][5][6][7][8]. From theoretical perspectives, they pose an exciting research topic in which competing interactions, reduced dimensionality, shape anisotropy, etc., lead to novel collective behaviours [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Hysteresis in Two Dimensional Arrays of Magnetic Nanoparticles

Anand

2021

Preprint

View full text Add to dashboard Cite

We perform computer simulations to probe the magnetic hysteresis in a two-dimensional (L x ×L y ) assembly of magnetic nanoparticles as a function of dipolar interaction strength h d , temperature T , aspect ratio A r = L y /L x , and the applied alternating magnetic field's direction. In the absence of magnetic interaction (h d ≈ 0) and thermal fluctuations (T = 0 K), the hysteresis follows the Stoner and Wohlfarth model, as expected. For weak dipolar interaction and substantial temperature, the hysteresis has the dominance of superparamagnetic behaviour, irrespective of the applied magnetic field's direction and A r . Interestingly, the hysteresis curve has all the characteristics of antiferromagnetic interaction dominance for A r ≤ 6 and considerable dipolar interaction strength (h d > 0.2), which is independent of applied magnetic direction. When the magnetic field is applied along the system's shorter axis (x-direction), a non-hysteresis straight line is observed with large h d . In the case of the magnetic field applied along the long axis of the sample (y-direction), ferromagnetic interaction dominates the hysteresis for large h d and A r > 6. Irrespective of h d and applied magnetic field's direction, the coercive field µ o H c and remanence M r are minimal for A r ≤ 6 and significant temperature. They are found to increase with h d when A r is enormous.Remarkably, the variation of hysteresis loop area E H as a function of these parameters is the same as that of the coercive field variation. We believe that the concepts presented in this work are relevant in various technological applications such as spintronics and magnetic hyperthermia, in which such self-assembled nanoparticle arrays are ubiquitous.

show abstract

Section: Introductionmentioning

confidence: 99%

Hysteresis in Two Dimensional Arrays of Magnetic Nanoparticles

Anand

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…In Fig. (6), we study the magnetic relaxation characteristics in a highly anisotropic system A r = 400.0. It corresponds to a one-dimensional chain of MNPs.…”

Section: Simulations Resultsmentioning

confidence: 99%

“…Two-dimensional assemblies of magnetic nanoparticles (MNPs) have received significant attention due to their exciting properties and numerous technological applications [1][2][3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Magnetization Reversal in Two-dimensional Ensemble of Nanoparticles with Positional Defects

Anand¹

2021

Preprint

View full text Add to dashboard Cite

We study relaxation behaviour in the two-dimensional assembly of magnetic nanoparticles (MNPs) with aligned anisotropy axes and positional defects. The anisotropy axes orientation and disorder strength is changed by varying α and ∆, respectively. The magnetization decay does not depend on the aspect ratio A r of the system and ∆ for small dipolar interaction strength h d = 0.2. Remarkably, the magnetization decays rapidly for considerable h d with negligible ∆ and A r = 1.0. The dipolar interaction of enough strength promotes antiferromagnetic coupling in square ensembles of MNPs. There is a prolonged magnetization decay for large ∆ because of enhancement in ferromagnetic coupling. Notably, magnetization relaxes slowly for α < α even with moderate h d and a significant A r . Interestingly, the slowing down of the magnetic relaxation shifts to a lower α with h d = 1.0. The magnetization ceases to relax for α ≤ 60 • and h d ≤ 0.6 due to large shape anisotropy with A r = 400.0. Remarkably, a majority of the magnetic moment reverses its direction by 180 • for α > 60 • and large h d , resulting in the negative magnetization. The effective Néel relaxation time τ N also depends strongly on these parameters. τ N depends weakly on α and ∆ for h d ≤ 0.2, irrespective of A r . On the other hand, τ N decreases with α for significant h d provided α is greater than 45 • because of antiferromagnetic coupling dominance. In a highly anisotropic system, there is an enhancement in τ N with α (≤ 30 • ) even with moderate h d . While for α > 30 • , τ N decreases with α. These observations are useful in novel materials, spintronics based applications, etc.

show abstract

“…In Fig. (6), we study the hysteresis response with a highly anisotropic system A r = 400, which corresponds to a one-dimensional chain of MNPs. MNPs stays in the superparamagnetic regime for small dipolar interaction strength even with huge A r , resulting in the minimal hysteresis loop area.…”

Section: Simulations Resultsmentioning

confidence: 99%

“…Two-dimensional ensembles of magnetic nanoparticles (MNPs) are one of the essential classes of nanostructures due to their exciting physics and various technological applications [1][2][3][4][5][6]. Their importance for fundamental research stems from multiple factors such as low dimensionality and a significant contribution from increased surface atoms, resulting in intriguing magnetic properties not observed in the bulk systems [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Controlling Dipolar Interaction Effect in Two-Dimensional Magnetic Nanostructures

Anand

2021

Preprint

View full text Add to dashboard Cite

We investigate the dependence of magnetic properties on the out-of-plane disorder strength ∆, dipolar interaction strength h d in two-dimensional (l x × l y ) ensembles of nanoparticles using numerical simulations. Such positional defects are redundantly observed in experiments. The superparamagnetic character is dominant with negligible and weak interaction strength h d , irrespective of ∆ and aspect ratio of the system A r = l y /l x . The double-loop hysteresis curve, characteristics of antiferromagnetic coupling dominance, emerges with large h d and ∆(%) ≤ 5 in the square-like nanoparticles' assays. Remarkably, the dipolar interaction of sufficient strength drives the magnetic order from antiferromagnetic to ferromagnetic with large ∆ and A r ≤ 4.0, resulting in an enhancement in the hysteresis loop area. On the other hand, the ferromagnetic coupling gets increased with h d in systems with huge A r . Consequently, the hysteresis loop is enormous, even with moderate h d . The variation of the coercive field µ o H c , remanence M r , and amount of heat released E H (due to the hysteresis) with these parameters also suggests the transformation of nature dipolar interaction. They are significant even with large h d and smaller A r , indicating the antiferromagnetic coupling dominance. Interestingly, there is an enhancement in these with ∆ and large h d due to ferromagnetic interaction. Notably, they are very significant even with moderate h d in the highly anisotropic system and external field along the long axis of the sample. These results could help the experimentalist in explaining the unusual hysteresis characteristics observed in such systems and should also be beneficial in diverse applications such as data storage, magnetic hyperthermia, etc.

show abstract

Dielectric Modulation of Two-Dimensional Dipolar Materials

Cited by 12 publications

References 44 publications

Hysteresis in Two Dimensional Arrays of Magnetic Nanoparticles

Hysteresis in Two Dimensional Arrays of Magnetic Nanoparticles

Magnetization Reversal in Two-dimensional Ensemble of Nanoparticles with Positional Defects

Controlling Dipolar Interaction Effect in Two-Dimensional Magnetic Nanostructures

Contact Info

Product

Resources

About