A5013846035- Advanced Condensed Matter Physics
- Theoretical and Computational Physics
- Quantum many-body systems
- Physics of Superconductivity and Magnetism
- Magnetic properties of thin films
- Magnetic and transport properties of perovskites and related materials
- Graphene research and applications
- Carbon Nanotubes in Composites
- Advanced Materials and Mechanics
- Multiferroics and related materials
- Cold Atom Physics and Bose-Einstein Condensates
- Material Dynamics and Properties
- Algebraic structures and combinatorial models
- Liquid Crystal Research Advancements
- Opinion Dynamics and Social Influence
- Geomagnetism and Paleomagnetism Studies
- Complex Systems and Time Series Analysis
- Topological Materials and Phenomena
- Personal Information Management and User Behavior
- Nanopore and Nanochannel Transport Studies
- Nonlinear Photonic Systems
- High-pressure geophysics and materials
- Advanced Thermodynamics and Statistical Mechanics
- Geology and Paleoclimatology Research
- Mechanical and Optical Resonators
Los Alamos National Laboratory
2016-2025
California State Polytechnic University
2023
Universidade Federal de Viçosa
2021
Los Alamos National Security (United States)
2013-2021
University of Virginia
2021
Institut de Nanociència i Nanotecnologia de la Universitat de Barcelona
2019
Universitat de Barcelona
2019
Material Sciences (United States)
2014-2015
Pennsylvania State University
2003-2010
Frustration in the presence of competing interactions is ubiquitous physical sciences and a source degeneracy disorder, giving rise to new interesting phenomena. Perhaps nowhere does it occur more simply than correlated spin systems, where has been studied most detail. In past few years, perspective opened study frustration through creation artificial frustrated magnetic systems. These materials consist arrays lithographically fabricated single-domain ferromagnetic nanostructures that behave...
In 1935, Pauling estimated the residual entropy of water ice with remarkable accuracy by considering degeneracy rule {\it solely at vertex level}. Indeed, his estimate works well for both three-dimensional pyrochlore lattice and two-dimensional six-vertex model, solved Lieb in 1967. The case honeycomb artificial spin is similar: its pseudo-ice rule, like Lieb's systems, simply extends a which already present vertices to global ground state. anisotropy magnetic interaction limits design...
Frustrated arrays of interacting single-domain nanomagnets provide important model systems for statistical mechanics, because they map closely onto well-studied vertex models and are amenable to direct imaging custom engineering. Although these manifestly athermal, we demonstrate that the properties both hexagonal square lattices can be described by an effective temperature based on magnetostatic energy arrays. This has predictive power moment configurations is intimately related how moments...
We analyze the rotational demagnetization of artificial spin ice, a recently realized array nanoscale single-domain ferromagnetic islands. Demagnetization does not anneal this model system into its antiferromagnetic ground state: moments have static disordered configuration similar to frozen state ice materials. demonstrate that athermal has an effective extensive degeneracy and we introduce formalism can predict populations local states in icelike with no adjustable parameters.
We study ac demagnetization in frustrated arrays of single-domain ferromagnetic islands, exhaustively resolving every (Ising-like) magnetic degree freedom the systems. Although net moment is brought near zero by a protocol with sufficiently small step size, final magnetostatic energy demagnetized array continues to decrease for finer-stepped protocols and does not extrapolate ground-state energy. The resulting complex disordered state can be described maximum-entropy ensemble constrained...
Complex behavior in soft materials comes from the interactions between its components and geometrical constraints associated with lattice structures. Frustration is one classical example of such complex leading to a plethora phases new phenomena. In this Colloquium case ice rule discussed how it reflects other materials.
By fabricating magnetic structures into nanoscale arrays, physicists can directly visualize how condensed-matter systems accommodate competing interactions among dipole moments and other degrees of freedom.
A reconfigurable spin ice Spin ices, magnetic systems in which local spins respect the so-called rules, can occur natural materials or be engineered patterned arrays. King et al . used superconducting qubits to implement a two-dimensional artificial ice. By changing strength and ratio of couplings, researchers were able access variety ground states. Arranging boundary an antiferromagnetic configuration then flipping one those generated monopole system’s interior. —JS
Artificial spin ice systems are lithographically prepared arrays of interacting nanoscale magnetic moments with collective behavior resulting from the chosen array geometry. These many-body unusual in that their simple constituent elements can be configured to design interactions exquisite control. They then probed experimentally over a remarkably large range time scales and length scales, including imaging individual moments. The study artificial has broadened well beyond original focus on...
Abstract Ordered mechanical systems typically have one or only a few stable rest configurations, and hence are not considered useful for encoding memory. Multistable history-dependent responses usually emerge from quenched disorder, example in amorphous solids crumpled sheets. In contrast, due to geometric frustration, periodic magnetic can create their own disorder espouse an extensive manifold of quasi-degenerate configurations. Inspired by the topological structure frustrated artificial...
A double-walled carbon nanotube is used to study the radial charge distribution on positive inner electrode of a cylindrical molecular capacitor. The outer shell bromine anions. Resonant Raman scattering from phonons each reveals distribution. self-consistent tight-binding model confirms observed Faraday cage effect, i.e., most resides wall, even when this wall was originally semiconducting and metallic.
We have studied frustrated kagome arrays and unfrustrated honeycomb of magnetostatically-interacting single-domain ferromagnetic islands with magnetization normal to the plane. The measured pairwise spin correlations both lattices can be reproduced by models based solely on nearest-neighbor correlations. array has qualitatively different magnetostatics but identical lattice topology previously-studied 'artificial ice' systems composed in-plane moments. two show striking similarities in...
We experimentally demonstrate that arrays of interacting nanoscale ferromagnetic islands, known as artificial spin ice, develop reproducible microstates upon cycling an applied magnetic field. The onset this memory effect is determined by the strength field relative to array coercivity. Specifically, when almost exactly equal coercivity, several training cycles are required before achieves a nearly completely repeatable microstate, whereas stronger or weaker than microstate achieved after...
Topological phases of spin liquids with constrained disorder can host a kinetics fractionalized excitations. However, spin-liquid distinct kinetic regimes have proven difficult to observe experimentally. Here we present realization kagome ice in the superconducting qubits quantum annealer, and use it demonstrate field-induced crossover between phases. Employing fine control over local magnetic fields, show evidence both Ice-I phase an unconventional Ice-II phase. In latter, charge-ordered...
We report a study of demagnetization protocols for frustrated arrays interacting single domain permalloy nanomagnets by rotating the in changing magnetic field. The most effective is achieved not only stepping field strength down while sample rotating, but combining each step with an alternation direction. By contrast, linearly decreasing or without alternating direction leaves larger remanent moment. These results suggest that non-monotonic variations magnitude around and below coercive are...
We study the impact of geometry on magnetostatically frustrated single-domain nanomagnet arrays. examine square and hexagonal lattice arrays, as well a brickwork that combines anisotropy topology lattice. find more highly allows for most thorough minimization magnetostatic energy, pair-wise correlations between moments differ qualitatively lattices, although they share same topology. The results indicate symmetry local interaction is important than overall in accommodation interactions.