Article
Physics, Multidisciplinary
N. S. Bingham, X. Zhang, J. Ramberger, O. Heinonen, C. Leighton, P. Schiffer
Summary: In this study, we investigated the temperature and magnetic field dependence of the total magnetic moment of large-area permalloy artificial square spin ice arrays. Our findings showed that the hysteresis behavior and temperature dependence are consistent with the Stoner-Wohlfarth model, with deviations observed at small lattice spacing due to interisland interactions. Through micromagnetic simulations, we further explored the complex magnetization reversal induced by interisland interactions, highlighting the critical role of island shapes in tuning the physical properties of artificial spin ice structures and other nanomagnet systems.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Kevin Hofhuis, Charlotte F. Petersen, Michael Saccone, Scott Dhuey, Armin Kleibert, Sebastiaan van Dijken, Alan Farhan
Summary: Low-energy configurations in a two-dimensional array of Ising-type dipolar coupled nanomagnets were studied, revealing a competition between ferromagnetic and vortex-dominated orders that can be controlled by adjusting lattice parameters and competing interactions.
Article
Materials Science, Multidisciplinary
J. P. Clancy, H. Gretarsson, A. Lupascu, J. A. Sears, Z. Nie, M. H. Upton, Jungho Kim, Z. Islam, M. Uchida, D. G. Schlom, K. M. Shen, Young -June Kim
Summary: We investigated the magnetic and spin-orbit excitations of ultrathin epitaxial films of Ba2IrO4 using resonant inelastic x-ray scattering, and compared them with their sister compound Sr2IrO4. Due to the 180 degrees Ir-O-Ir bond, the magnon and spin orbiton in Ba2IrO4 have a significantly larger bandwidth, making it challenging to describe these excitations as separate quasiparticles. Both types of excitations are sensitive to epitaxial strain. Additionally, the d-level inversion observed in Sr2IrO4 is not present in Ba2IrO4, as predicted by recent theoretical studies. Our results highlight the substantial differences in the magnetic properties of Ba2IrO4 and Sr2IrO4, suggesting a need for a careful examination of these materials considering electron itinerancy.
Article
Physics, Fluids & Plasmas
Kseniia Makarova, Vladislav Strongin, Iuliia Titovets, Aleksandr Syrov, Ivan Zinchenko, Victor Samoylov, Kevin Hofhuis, Michael Saccone, Aleksandr Makarov, Alan Farhan, Konstantin Nefedev
Summary: The study investigates the properties of low-energy states of ferromagnetic nanoislands on the Cairo lattice using an interacting Ising-like magnetic dipoles model to explore the influence of geometrical frustration. The analysis reveals nonmonotonic behavior in the ground-state energy of the Cairo lattice and the presence of specific closed pentagons and magnetic order rules in the ground-state configurations.
Article
Multidisciplinary Sciences
Gary W. Paterson, Gavin M. Macauley, Rair Macedo
Summary: The study found that a simple point dipole model works relatively well for square ice, but fails to replicate the properties observed in recent experiments with pinwheel ice. Parameterization of the reversal barrier in a Stoner-Wohlfarth model improves upon this, but does not fully capture the physics of ferromagnetic coupling observed in pinwheel structures.
ADVANCED THEORY AND SIMULATIONS
(2021)
Article
Physics, Condensed Matter
J. C. Flores
Summary: This article investigates the dispersion relation and degrees of freedom of elementary excitations in anomalous interfaces. The example of magnons at the junction between ferromagnetic and antiferromagnetic materials is discussed, and the behavior at high temperatures is examined.
PHYSICA B-CONDENSED MATTER
(2022)
Article
Multidisciplinary Sciences
Bin Gao, Tong Chen, Xiao-Chuan Wu, Michael Flynn, Chunruo Duan, Lebing Chen, Chien-Lung Huang, Jesse Liebman, Shuyi Li, Feng Ye, Matthew B. Stone, Andrey Podlesnyak, Douglas L. Abernathy, Devashibhai T. Adroja, Manh Duc Le, Qingzhen Huang, Andriy H. Nevidomskyy, Emilia Morosan, Leon Balents, Pengcheng Dai
Summary: Magnetic order can still occur in materials with spin-singlet ground state due to exchange interactions mixing excited crystal electric field states. The study investigates Ni2Mo3O8 and finds that crystal electric field states in both the paramagnetic and antiferromagnetic states exhibit dispersive excitations.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Carolina Rodriguez-Gallo, Antonio Ortiz-Ambriz, Cristiano Nisoli, Pietro Tierno
Summary: Controlling the ice rule through geometry transformations, the topological properties of colloidal ice are studied. It is found that a geometric transformation from Shakti to Cairo leads to a breakdown of the ice rule, and a transfer of topological charge among sublattices is observed, which can be controlled in sign and intensity.
COMMUNICATIONS PHYSICS
(2023)
Article
Physics, Applied
N. Rougemaille, B. Canals
Summary: In this study, the sixteen vertex model is investigated to describe the square ice magnetic structure factor phenomenologically. Monte Carlo simulations show that the high-temperature regime of square ice can be seen as a superposition of magnetic structure factors from two other models. The empirical arguments provided explain the presence of intensity in certain regions of reciprocal space and the absence of it in others, as well as why pinch points only appear for certain wavevectors.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Multidisciplinary
M. Goryca, X. Zhang, J. Li, A. L. Balk, J. D. Watts, C. Leighton, C. Nisoli, P. Schiffer, S. A. Crooker
Summary: Artificial spin ices can host plasmalike regimes with high density of mobile magnetic monopoles, dynamics of which are most diffusive in the plasma regime. This provides a new paradigm for probing the physics of effective magnetic charges in synthetic matter, with on-demand monopole regimes having field-tunable densities and dynamic properties.
Article
Multidisciplinary Sciences
Hao-Ting Chin, Jiri Klimes, I-Fan Hu, Ding-Rui Chen, Hai-Thai Nguyen, Ting-Wei Chen, Shao-Wei Ma, Mario Hofmann, Chi-Te Liang, Ya-Ping Hsieh
Summary: The authors observe ferroelectric properties of water ice in a two-dimensional phase under confinement between two graphene layers, providing important insights for understanding condensed matter.
NATURE COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Christopher D. Williams, Zixuan Wei, Mohd Rafie bin Shaharudin, Paola Carbone
Summary: In this study, molecular dynamics simulations were used to assess the stability of graphene nanochannels and the behavior of water confined in these channels. It was found that the presence of water prevented the collapse of nanochannels and resulted in the formation of a mobile, liquid monolayer. This finding contradicts classical simulations but is supported by experiments and first-principles simulations.
Article
Multidisciplinary Sciences
J. M. Ni, Y. Y. Huang, E. J. Cheng, Y. J. Yu, B. L. Pan, Q. Li, L. M. Xu, Z. M. Tian, S. Y. Li
Summary: Spin liquids are exotic states with highly entangled and fluctuating spins in frustrated systems, and they do not exhibit spontaneous symmetry breaking down to zero temperature. Excitations like magnetic monopoles, visons, and photons may emerge from quantum spin ice states, which are a special type of spin liquids found in pyrochlore lattices. The insulating nature of spin liquids is challenged by the metallic spin liquid Pr2Ir2O7, located at a zero-field quantum critical point. Thermal conductivity measurements on Pr2Ir2O7 reveal the absence of breakdown of Landau quasiparticles at the quantum critical point and the lack of mobile fermionic excitations, which helps constrain the description of quantum criticality in this material. Surprisingly, while the specific heats show anisotropy with respect to magnetic field directions, the thermal conductivities exhibit a giant but isotropic response, suggesting the importance of quadrupolar interactions and quantum fluctuations in determining the true ground state of the material.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Multidisciplinary
A. D. King, J. Coraux, B. Canals, N. Rougemaille
Summary: This study experimentally observes the phenomenon of the arctic circle for the first time, revealing the presence of a spin liquid and isolated monopole excitations. These findings are significant for understanding the phase transition between ordered and disordered states in condensed matter physics, as well as topological phase transitions.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Applied
Rehana Begum Popy, Julia Frank, Robert L. Stamps
Summary: In this study, the possible magnetic behaviors of bilayer artificial spin ice are examined using numerical simulations. The impact of long-range dipolar coupling on magnetization dynamics is investigated by varying the layer separation and rotation. Unusual magnetic ordering is predicted for certain angles that define lateral spin superlattices in the bilayer systems.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Multidisciplinary Sciences
T. S. de Paiva, J. H. Rodrigues, L. A. S. Mol, A. R. Pereira, J. Borme, P. P. Freitas, C. I. L. de Araujo
SCIENTIFIC REPORTS
(2020)
Article
Physics, Condensed Matter
R. C. Silva, R. L. Silva, A. R. Pereira
Summary: This paper investigates a magnetic racetrack system composed of three materials with different properties. Skyrmions and antiskyrmions are created in their respective sectors and impelled to the interface by applying a spin-polarized current, forming a skyrmion-antiskyrmion pair. The engineered racetrack can support a sequence of several skyrmion-antiskyrmion pair structures in motion, forming a current.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Physics, Applied
Fernando F. Martins, Teonis S. Paiva, Daniel G. Duarte, Joao H. Rodrigues, Lucas A. S. Mol, Clodoaldo I. L. de Araujo
Summary: In this work, the screening effect of magnetic monopole and dipole by the presence of aluminum cover layer on square artificial spin ice systems is presented. Experimental results show that the presence of aluminum decreases the strengths of emergent magnetic monopole and dipole. This screening effect can be utilized for designing devices with different magnetic monopole mobility or for selectively activating samples close to superparamagnetic regime.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Multidisciplinary
R. G. M. Rodrigues, B. Costa, L. A. S. Mol
Summary: The use of partition function zeros in the study of phase transitions has been found to be reliable, even with parameter variations. A proposal to address the potential convergence issues of the original algorithm has also been presented.
BRAZILIAN JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
R. L. Silva, R. C. Silva, A. R. Pereira
Summary: This study compares the behavior of antiferromagnetic skyrmions and bimerons in a hurdle race by setting obstacles in their lanes. It is found that the sprint hurdles between spin textures can be controlled by adjusting the class, number, and size of the obstacles.
Article
Physics, Multidisciplinary
R. C. Silva, R. L. Silva, A. R. Pereira
Summary: This study used Monte Carlo and spin dynamics techniques to investigate the impact of defects on stable vortex-like magnetization in ferromagnetic nanodisks. The findings show that individual magnetic dot defects can attract or repel the antiferromagnetic vortex core in the system.
Article
Materials Science, Multidisciplinary
R. C. Silva, R. L. Silva, V. L. Carvalho-Santos, W. A. Moura-Melo, A. R. Pereira
Summary: In this study, we investigate the dynamics of two skyrmions in an antiferromagnetic bilayer system. We find that the skyrmions can form a bound state through ferromagnetic exchange coupling and analyze how their dynamics are influenced by the application of an electric current. We also examine the conditions for the nucleation of the bound state and analyze its robustness under different circumstances.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
R. L. Silva, R. C. Silva, A. R. Pereira
Summary: This study analyzes the biskyrmion with two cores in frustrated ferromagnetic racetracks, and investigates the biskyrmion dynamics induced by a spin-polarized current. The biskyrmion Hall effect is compared with the usual skyrmion Hall effect, and the chance of biskyrmion fractionalization in a single skyrmion is studied.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
R. L. Silva, R. C. Silva, W. A. Moura-Melo, A. R. Pereira
Summary: This work investigates the interaction between spin texture and lattice defects, focusing on the dynamics of skyrmions in antiferromagnetic nanodisks influenced by a random distribution of magnetic impurities. The study reveals that the presence of impurities may deform or even destroy the antiferromagnetic skyrmion, and the type of impurity determines the extent of this effect.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Physics, Applied
R. L. Silva, R. C. Silva, A. R. Pereira
Summary: The topological stability of skyrmions is crucial for their use in new technologies. The controlled manipulation of skyrmion configuration, such as polarity and chirality, may play a significant role. Investigating the skyrmion oscillatory motion in a hybrid nanodisk can provide new functionalities for skyrmion-based logic devices.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Physics, Multidisciplinary
R. L. Silva, R. C. Silva, A. M. Franca-Neto, A. R. Pereira
Summary: In this study, an antiferromagnetic skyrmion crystal was created using a staggered magnetic field. The influence of spin vacancies on the creation of the skyrmion crystal was examined. Furthermore, the dynamics of skyrmions in a hybrid racetrack were explored.
Article
Materials Science, Multidisciplinary
R. L. Silva, R. C. Silva, A. R. Pereira, Cameron A. Mceleney, Rair Macedo
Summary: This article explores the process of splitting biskyrmions into single skyrmions using spin wave excitations in a frustrated two-dimensional ferromagnet, and investigates the splitting processes of both Bloch and Neel types of biskyrmions.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
R. L. Silva, R. C. Silva, Y. Masaki
Summary: In this study, we investigate the dynamics of an isolated bimeron in an antiferromagnetic system in the presence of magnetic defects. By numerically solving the Landau-Lifshitz-Gilbert equation, we find that the bimeron exhibits breathing dynamics and transverse motion due to the defect potential. We also analyze the potential landscapes arising from the interaction between the bimeron and a defect, providing a qualitative understanding of the obtained dynamics.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Physics, Fluids & Plasmas
R. G. M. Rodrigues, B. Costa, L. A. S. Mol
Summary: A formulation based on energy probability distribution zeros has been proposed to reduce polynomial degree while maintaining accuracy, making it computationally cheaper than EPD zeros and enabling the study of systems using partition function zeros. This method can also be easily extended to study phase transitions in external fields while preserving its improvements.
Article
Physics, Applied
R. L. Silva, R. C. Silva, A. R. Pereira, W. A. Moura-Melo
JOURNAL OF APPLIED PHYSICS
(2020)