Spin-orbit coupling (SOC) profoundly affects the band structure of a material, and is at the heart of magnetic anisotropy, the spin Hall effect, and the Dzyaloshinskii-Moriya interaction. Since in the simplest picture the SOC of a material increases $\propto$ $Z^4$, where $Z$ is the atomic number, there has recently been intense focus on systems containing relatively heavy non-magnetic metals...
Very general considerations suggest that critical itinerant ferromagnets display fluctuation-induced helimagnetism near to their quantum critical points. Evidence of this behaviour has been found in a number of materials, but often the experimental phase diagram is rather richer than that predicted by the minimal model. I will report calculations of the effects of adding spin and fermi surface...
In a paper published in 2006 [1], C.N.R. Rao and co-workers suggested that weak ferromagnetism was a ‘universal feature of otherwise nonmagnetic oxide nanoparticles’. As there were no magnetic impurities present, they assumed that the origin of the d-zero magnetism might be exchange interactions between localized electron spin moments resulting from oxygen vacancies at the nanoparticle...
Neutron diffraction and scattering based techniques play a substantial role in characterising and understanding physical phenomena, including magnetism, in various types of materials. These techniques are widely available to the scientific community, however bulk quantities of the materials are often required. The study of magnetism in thin films by neutron techniques is less common. The...
Magnons are the fundamental excitations in magnetic materials, and they can transport angular momentum without actual charge currents. Therefore, they are attractive for applications in energy efficient information technology, offering high operating frequencies up to the THz range. Here we present a novel scheme for magnon generation using spin currents and domain walls.
When a charge...
We present an analytical study on the spinmotive force (SMF) generated by translational motion of magnetic Skyrmion. A SMF refers to an electrical voltage emerged due to dynamical magnetic textures, which reflects the spatiotemporal variation of the magnetization. The dynamics of a Skyrmion thus can be detected by a SMF measurement, which may play an important role in future Skyrmion-based...
We present the synthesis, crystal structure, electric and magnetic properties of the spin-crossover salt [Mn(5-Cl-sal-N-1,5,8,12)]TCNQ1.5(2CH3CN), (I), containing distinct conductive and magnetic blocks along with the solvent acetonitrile molecules. As a magnetic unit it employs the Mn (III) ion with Schiff base ligands [Mn(5-Cl-sal-N-1,5,8,12)]ClO4 while the conducting unit is the π -...
The spin Seebeck effect – generation of a spin polarised current in a magnetic material subjected to a temperature gradient – is a magnetothermal effect that could be used for generation of pure spin currents for spintronic applications. It is most often detected indirectly by placing a heavy metal such as Pt in contact with the magnet and measuring the voltage generated by the inverse spin...
In ordinary magnetic insulators, elementary excitation from a magnetic ordered state is described by a magnon, which is a quantized spin wave. Magnons carry spin current and thermal current. In contrast, frustrated quantum magnets frequently exhibit non-trivial ground states and elementary excitations. Thus we expect that novel types of carriers would contribute to spin and thermal transport...
We theoretically describe non-equilibrium spin transport in metal-insulator interfaces. From the interface exchange interaction between the conduction electrons and the insulator spins, we derive semi-classical stochastic equations of motion for the spins. The non-equilibrium driving here originates from spin accumulation of the electrons at the interface. From the resulting equations of...
Collective spin excitations in quantum materials provide a revolutionary alternative for devices with improved performances and energy-efficiency, as they permit the transfer of information without requiring any movement of charge, thus eliminating the dominant source of energy dissipation.
Understanding how to manipulate these collective spin excitations would provide a foundation for the...
The magnetic insulator yttrium iron garnet (YIG) is used in microwave and optical technology. The record quality of its magnetization dynamics makes it also a promising material for classical and quantum information technology. Magnons, the elementary excitations of the magnetic order, can be studied in great detail by inelastic (Brillouin) light scattering experiments. Here, we present a...
Obtaining detailed information on interface structure and proximity effects in magnetic heterostructures is indispensable for understanding the mechanisms promoting the novel physical properties and functional behavior. We will present recent examples using the high sensitivity of neutron reflectometry to resolve structural and magnetic ordering across interfaces in layer systems and lateral...
The spin Seebeck effect (SSE) [1] attracts much attention due to possible application to thermal spin generators for driving spintronics devices. The SSE is observed through the generation of spin current in ferromagnets and ferrimagnets under a temperature gradient. Driving spin currents thermally could lead to the manufacturing of a compact magnetic source without using electric current or...
There exists a gap in the electromagnetic spectrum between 0.3 - 30 THz in which semiconductor and optical technologies fail to generate and detect radiation using chip-sized elements. However, antiferromagnets (AFM) and compensated ferrimagnets (CFiM) have resonance frequencies in this range, making them a viable solution. AFMs and CFiMs cannot easily be manipulated by external fields due to...
The spin Seebeck effect (SSE) [1] refers to the generation of a spin current in magnetic materials by a temperature gradient. In the SSE, a thermally generated magnon spin current in a magnet is converted into a conduction-electron spin current in a metal attached to the magnet via the interfacial spin-exchange interaction. The spin current is detected as an electric voltage via the inverse...
The coexistence of ferroelectricity and magnetism being considered for a long time mutually exclusive phenomena represent now a flourishing field of magnetoelectric multiferroicity. In particular, the magnetoelectric coupling is an intrinsic feature of the improper multiferroics where the electric polarization arises from the spiral magnetic ordering. The spirals are the result of competition...
The aim of this presentation is to theoretically propose an efficient way of spin current generation in so-called "topological Dirac seimetals (TDSMs)." TDSMs are characterized by pair(s) of doubly-degenerate nodal points (Dirac points) in momentum space that are protected by rotational symmetry around an axis, directly observed by angle-resolved photoemission spectroscopy (ARPES) in Na$_3$Bi...
Skyrmions constitute a new magnetic topology that occurs only under specific conditions of
temperature, applied magnetic fields, and only in certain chiral magnets lacking inversion
symmetry. Thanks to their topological stability and the low current density required for the
manipulation of their position, skyrmions constitute a valid alternative to domain walls as
information carriers in...
A heat current perpendicularly flowing to a magnetic field induces a transverse temperature gradient. This is the thermal Hall effect (THE). It was reported in the paramagnetic insulator, terbium-gallium-garnet (TGG) at low temperatures [1,2]. Since the TGG has a large band gap of several eV and then only phonons can carry the heat, it is called “phonon Hall effect (PHE)”. However, phonon does...
