A team of researchers from the DOE/Argonne National Laboratory and U.S. additional laboratories and universities have reported a mechanical response across a layered magnetic material tied to changing its electron spin. This response could have important applications in nanodevices requiring ultra-precise and fast motion control.

A little over a century ago, physicists Albert Einstein and Wander de Haas reported a surprising effect in ferromagnets: if you suspend an iron cylinder from a wire and expose it to a magnetic field, it will start rotating if you simply reverse the direction of the magnetic field. "Einstein and de Haas's experiment is almost like a magic show," said Haidan Wen, a physicist in the Materials Science and X-ray Science divisions of the U.S. Department of Energy's (DOE) Argonne National Laboratory. ​"You can cause a cylinder to rotate without ever touching it."

Researchers from Northwestern University and North Carolina State University have gained fascinating insights into the relationship between the spin-vibronic effect and intersystem crossing in molecules. The work could lead to new ways to control electron spin within molecules, and to more efficient energy capture that could be applied to various fields. 

The team presented coherence spectroscopy experiments that reveal the interplay between the spin, electronic and vibrational degrees of freedom that drive efficient singlet–triplet conversion in four structurally related dinuclear Pt(II) metal–metal-to-ligand charge-transfer (MMLCT) complexes. Photoexcitation activates the formation of a Pt–Pt bond, launching a stretching vibrational wavepacket. The molecular-structure-dependent decoherence and recoherence dynamics of this wavepacket resolve the spin–vibronic mechanism.

A team of scientists from the University of Minnesota Twin Cities has synthesized a thin film of a unique topological semimetal material that has the potential to generate more computing power and memory storage while using significantly less energy. The researchers were also able to closely study the material, leading to some fascinating findings about the physics behind its unique properties.

Much attention is put into developing the materials that power electronic devices. While traditional semiconductors are the technology behind most of today's computer chips, scientists are always looking for new materials that can generate more power with less energy to make electronics better, smaller, and more efficient. One such candidate for these new and improved computer chips is a class of quantum materials called topological semimetals. The electrons in these materials behave in different ways, giving the materials unique properties that typical insulators and metals used in electronic devices do not have. For this reason, they are being explored for use in spintronic devices, an alternative to traditional semiconductor devices that leverage the spin of electrons rather than the electrical charge to store data and process information.

A research team from Ames National Laboratory, National Institute of Standards and Technology (NIST), University of California Santa Barbara (UCSB), Iowa State University, University of Edinburgh, George Mason University and Oak Ridge National Laboratory (ORNL) recently conducted an investigation of the magnetism of TbMn₆Sn₆, a Kagome layered topological magnet. They found that the magnetic spin reorientation in the material occurs by generating increasing numbers of magnetically isotropic ions as the temperature increases.

Rob McQueeney, a scientist at Ames Lab and project lead, explained that TbMn₆Sn₆ has two different magnetic ions in the material, terbium and manganese. The direction of the manganese moments controls the topological state, "But it's the terbium moment that determines the direction that the manganese points," he said. "The idea is, you have these two magnetic species and it is the combination of their interactions which controls the direction of the moment."

Scientists at Cornell University, Washington University in St. Louis and University of Maryland have revealed a new phase of matter in candidate topological superconductors that could have significant consequences for condensed matter physics and for the field of quantum computing and spintronics.

The researchers discovered and visualized a crystalline yet superconducting state in a new and unusual superconductor, Uranium Ditelluride (UTe₂), using one of the world’s most powerful millikelvin Scanned Josephson Tunnelling Microscopes (SJTM). This “spin-triplet electron-pair crystal” is a previously unknown state of topological quantum matter.

Researchers from Cambridge University in the UK, Korea's DGIST and Harvard University in the U.S have shown that electron spins could become more efficient and easier to manage through a light-based approach using halide perovskite semiconductors. The team observed ultrafast spin-domain formation in polycrystalline halide perovskite thin films in response to irradiating the films with circularly polarized light at room temperature.

Photoinduced spin-charge interconversion in semiconductors, with spin-orbit coupling, could provide a route to spintronics that does not require external magnetic fields, which tend to be challenging to control. An electron can have two spin states, up or down, and these states can be used to store and process information. But manipulating spin states can be tricky, requiring the use of magnetic fields on perfectly ordered materials at extremely low temperatures to work.

Researchers at North Carolina State University (NCSU) have reported a new distinct form of silicon called Q-silicon which, among other interesting properties, is ferromagnetic at room temperature. The team's recent findings could lead to advances in quantum computing, including the creation of a spin qubit quantum computer that is based on controlling the spin of an electron.

“The discovery of Q-silicon having robust room temperature ferromagnetism will open a new frontier in atomic-scale, spin-based devices and functional integration with nanoelectronics,” said Jay Narayan, the John C. Fan Family Distinguished Chair in Materials Science and corresponding author of the paper describing the work.

Researchers from Oak Ridge National Laboratory (ORNL) have proposed a mechanism to control the magnetic properties of topological quantum material (TQM) by using magnetoelectric coupling: a mechanism that uses a heterostructure of TQM with two-dimensional (2D) ferroelectric material, which can dynamically control the magnetic order by changing the polarization of the ferroelectric material and induce possible topological phase transitions. 

The novel concept was demonstrated using the example of the bilayer MnBi₂Te₄ on ferroelectric In₂Se₃ or In₂Te₃, where the polarization direction of the 2D ferroelectrics determines the interfacial band alignment and consequently the direction of the charge transfer. This charge transfer, in turn, enhances the stability of the ferromagnetic state of MnBi₂Te₄ and leads to a possible topological phase transition between the quantum anomalous Hall (QAH) effect and the zero plateau QAH.

Researchers from the Hebrew University of Jerusalem in Israel have made a recent discovery that could change the face of spintronics research.

A spintronics device developed by Professor Capua's lab

They discovered that the most important equation used to describe magnetization dynamics, namely the Landau-Lifshitz-Gilbert (LLG) equation, also applies to the optical domain. Consequently, they found that the helicity-dependent optical control of the magnetization state emerges naturally from their calculations. This is a very surprising result since the LLG equation was considered to describe much slower dynamics and it was not expected to yield a meaningful outcome also at the optical limit.

Researchers from Purdue University, Pennsylvania State University and Japan's National Institute for Materials Science (NIMS) have reported electrically tunable moiré magnetism in twisted double bilayers (a bilayer on top of a bilayer with a twist angle between them) of layered antiferromagnet chromium triiodide. 

Using magneto-optical Kerr effect microscopy, the team observed the coexistence of antiferromagnetic and ferromagnetic order with non-zero net magnetization—a hallmark of moiré magnetism. Such a magnetic state extends over a wide range of twist angles (with transitions at around 0° and above 20°) and exhibits a non-monotonic temperature dependence. The researchers also demonstrated voltage-assisted magnetic switching. The observed non-trivial magnetic states, as well as control via twist angle, temperature and electrical gating, are supported by a simulated phase diagram of moiré magnetism.