The classical laws of physics are usually invariant under time reversal. Here, we reveal a novel class of magnetomechanical effects rigorously breaking time-reversal symmetry. These effects are based on the mechanical rotation of a hard magnet around its magnetization axis in the presence of friction and an external magnetic field, which we call spin revolution. The spin revolution leads to a variety of symmetry breaking phenomena including upward propulsion on vertical surfaces defying gravity as well as magnetic gyroscopic motion that is perpendicular to the applied force. The angular momentum of spin revolution differs from those of the magnetic field, the magnetic torque, the rolling axis, and the net torque about the rolling axis. The spin revolution emerges spontaneously, without external rotations, and offers various applications in areas such as magnetism, robotics and energy harvesting.
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http://dx.doi.org/10.1038/s41598-022-17766-z | DOI Listing |
J Phys Chem C Nanomater Interfaces
January 2025
Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea.
Precise description of the interaction between molecular oxygen and metal surfaces is one of the most challenging topics in quantum chemistry. In this work, we use low-temperature scanning tunneling microscopy (STM) to identify and characterize an adsorption state of molecular oxygen that coordinates to three Ag atoms (μ) on Ag(100). Surprisingly, μ-O cannot be identified as a stable configuration with generalized gradient approximation (GGA)-level density functional theory (DFT) calculations.
View Article and Find Full Text PDFNano Lett
January 2025
Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea.
We demonstrate the reversible control of interactions between a local molecular spin, hosted within an iron phthalocyanine (FePc) molecule, and the conduction electrons of a supporting Au(111) surface. Using the tip of a scanning tunneling microscope, we deliberately and reversibly manipulate the adsorption configuration of the molecule relative to the underlying substrate lattice. Different rotation configurations lead to noticeable changes in the differential conductance measured on the FePc molecules.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Ronin Institute, Montclair, New Jersey 07043, USA.
The Rashba effect in a nonmagnetic condensed-matter system is described by the reduction of point-group symmetries. The inversion, two-fold rotation, and reflection symmetries transforming the wavevector to - are identified as the origin of a degenerate state according to the time-reversal symmetry. The lack of these symmetries in a bulk system or the breaking of these in a surface system is then identified as the origin of a nondegenerate state.
View Article and Find Full Text PDFJ Sports Sci
January 2025
Institute of Biomechanics and Orthopaedics, German Sport University, Cologne, Germany.
In snowboard freestyle, rotation is the key indicator of trick difficulty, encouraging riders to perform tricks with more rotation. In many cases, snowboarders learn and practice tricks using training tools such as trampolins and/or landingbags before they transfer this tricks on-snow. It has not yet been scientifically investigated which movement parameters are primarily responsible for the acquisistion of increasingly difficult cork tricks.
View Article and Find Full Text PDFACS Appl Electron Mater
January 2025
Department of Applied Physics, National Pingtung University, No. 4-18, Minsheng Road, 90044 Pingtung, Taiwan.
This study introduces a simple approach to dynamically control multilevel optical ellipticity in ferrimagnetic GdFeCo alloys by switching the spin orientation through Joule heating induced by electrical current, with the assistance of a low magnetic field of 3.5 mT. It is demonstrated that selecting specific compositions of Gd (FeCo) alloys, with magnetic compensation temperatures near or above room temperature, allows for significant manipulation of the circular dichroism (CD) effect.
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