What are skyrmions used for?
Magnetic materials/data storage The small size and low energy consumption of magnetic skyrmions make them a good candidate for future data-storage solutions and other spintronics devices. Researchers could read and write skyrmions using scanning tunneling microscopy.
How are skyrmions formed?
There are several ways to create skyrmions. Some appear spontaneously due to the dimensions or geometry of the material, while others are formed by external interference, such as the application of an electric current or magnetic pulses. To date, however, no controlled method for generating skyrmions has been found.
Why skyrmions?
The tiny whirlpools are called skyrmions, named after Tony Skyrme, the British physicist who predicted their existence in 1962. Their small size and sturdy nature—like knots that are hard to undo—have given rise to a rapidly expanding field devoted to understanding them better and exploiting their strange qualities.
What is topological Hall effect?
Topological Hall effect (THE) originates from the real-space Berry phase that an electron gains when its spin follows the spatially varying non-trivial magnetization textures, such as skyrmions.
What is spin texture?
The archetypal topological spin texture is a small, swirling magnetic knot known as a magnetic skyrmion (Fig. 1). In a skyrmion, the orientation of spins rotates progressively from the up direction at the edge of the texture to the down direction at the centre, or vice versa.
What is topological material?
Topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. The bulk of such materials is insulating but the surface can conduct electric current with well-defined spin texture.
Are Magnons bosons?
Magnons carry a fixed amount of energy and lattice momentum, and are spin-1, indicating they obey boson behavior.
Why skyrmions could have a lot in common with glass and high temperature superconductors?
Because they are so stable and so tiny – about 1,000 times the size of an atom – and are easily moved by applying small electric currents, he said, “there are lots of ideas about how to harness them for new types of computing and memory storage technologies that are smaller and use less energy.”
What is Dzyaloshinskii Moriya interaction?
The Dzyaloshinskii-Moriya interaction (DMI) is an antisymmetric exchange interaction that stabilizes chiral spin textures. It is induced by inversion symmetry breaking in noncentrosymmetric lattices or at interfaces.
How do you plot a spin texture?
To plot 2D spin texture, we require a 2D -grid centered a certain special -point in Brillouin zone near which we want to examine the spin-texture in -space (see section k-mesh generator regarding generation of 2D -mesh). One could also plot spin texture using arrows instead of a heat map.
What are topological properties of materials?
Topology is a branch of mathematics where properties of objects that are invariant under smooth deformations are studied. Materials properties which are invariant under topological transformations property are known as topological materials. Topological insulators (TIs) are insulating in bulk and conducting at surface.
Why are topological materials important?
Topological materials promise potentially useful applications, such as more energy-efficient microelectronic components, better catalysts, improved thermoelectric converters, or new magnetic storage media.
What is spin wave and magnons?
From the equivalent quasiparticle point of view, spin waves are known as magnons, which are bosonic modes of the spin lattice that correspond roughly to the phonon excitations of the nuclear lattice. As temperature is increased, the thermal excitation of spin waves reduces a ferromagnet’s spontaneous magnetization.
What are magnons explain?
magnon, small quantity of energy corresponding to a specific decrease in magnetic strength that travels as a unit through a magnetic substance. Related Topics: quasiparticle spin wave. See all related content → In a magnetic substance, such as iron, each atom acts as a small individual magnet.
What is the critical temperature of a superconductor?
The critical temperature (Tc), or the temperature under which a material acts as a superconductor, is an essential concern. For most materials, it is between absolute zero and 10 Kelvin, that is, between -273 Celsius and -263 Celsius, too cold to be of any practical use.
How does superconducting transition temperature vary with magnetic field?
The vast majority of the known superconductors have transition temperatures that lie between 1 K and 10 K. Of the chemical elements, tungsten has the lowest transition temperature, 0.015 K, and niobium the highest, 9.2 K. The transition temperature is usually very sensitive to the presence of magnetic impurities.
What is Superexchange interaction?
Superexchange is a result of the electrons having come from the same donor atom and being coupled with the receiving ions’ spins. If the two next-to-nearest neighbor positive ions are connected at 90 degrees to the bridging non-magnetic anion, then the interaction can be a ferromagnetic interaction.
What is Rashba spin coupling?
The Rashba spin-orbit coupling is typical for systems with uniaxial symmetry, e.g., for hexagonal crystals of CdS and CdSe for which it was originally found and perovskites, and also for heterostructures where it develops as a result of a symmetry breaking field in the direction perpendicular to the 2D surface.
Which are topological properties?
A topological property is defined to be a property that is preserved under a homeomorphism. Examples are connectedness, compactness, and, for a plane domain, the number of components of the boundary. The most general type of objects for which homeomorphisms can be defined are topological spaces.…
What is the meaning of magnon?
A magnon is a quasiparticle, a collective excitation of the electrons’ spin structure in a crystal lattice. In the equivalent wave picture of quantum mechanics, a magnon can be viewed as a quantized spin wave.
What is a magnetic skyrmion?
The first set of definitions for magnetic skyrmions is a superset of the second, in that it places less stringent requirements on the properties of a magnetic spin texture. This definition finds a raison d’être because topology itself determines some properties of magnetic spin textures, such as their dynamical responses to excitations.
What is a skyrmion?
Skyrmions can be formed in magnetic materials in their ‘bulk’ such as in MnSi, or in magnetic thin films. They can be achiral, or chiral (Fig. 1 a and b are both chiral skyrmions) in nature, and may exist both as dynamic excitations or stable or metastable states.
Why is the skyrmion magnetic configuration predicted to be stable?
The skyrmion magnetic configuration is predicted to be stable because the atomic spins which are oriented opposite those of the surrounding thin-film cannot ‘flip around’ to align themselves with the rest of the atoms in the film, without overcoming an energy barrier.
What can we learn from dynamical magnetic skyrmions?
The dynamical magnetic skyrmion exhibits strong breathing which opens the avenue for skyrmion-based microwave applications. Simulations also indicate that the position of magnetic skyrmions within a film/nanotrack may be manipulated using spin currents or spin waves.