Phys.org October 28, 2023 In some non- and paramagnetic systems, a large phonon magnetic moment is found due to coupling with electronic excitations. However, for magnetically ordered systems, a correspondingly large moment has not yet been discovered, and the roles of many-body correlations and fluctuations in phonon magnetism remain unclear. Researchers in China found a phonon magnetic moment that was enhanced by critical fluctuations in Fe2Mo3O8. Combining magneto-Raman spectroscopy and inelastic neutron scattering measurements, they showed that a pair of low-lying chiral phonons carried large magnetic moments. Once the system was driven to a ferrimagnetic phase, they observed a splitting […]
Tag Archives: Antiferromagnets
Scientists discover novel way of reading data in antiferromagnets, unlocking their use as computer memory
Nanowerk August 14, 2023 The Berry curvature and quantum metric are the imaginary part and real part, respectively, of the quantum geometric tensor which characterizes the topology of quantum states. The former is known to generate a zoo of important discoveries such as quantum Hall effect and anomalous Hall effect (AHE), while the consequences of the quantum metric have rarely been probed by transport. An international team of researchers (Singapore, Israel, China, Japan) has found quantum metric-induced nonlinear transport, including both nonlinear AHE and diode-like nonreciprocal longitudinal response, in thin films of a topological antiferromagnet, MnBi2Te4. They have revealed that […]
Approaching the terahertz regime
Science Daily January 19, 2023 Tunnelling magnetoresistance (TMR) is considered to be proportional to spin polarization at the interface and has been studied primarily in ferromagnets. An international team of researchers (Japan, Canada) observed TMR in an all-antiferromagnetic tunnel junction consisting of Mn3Sn/MgO/Mn3Sn. They made measurements using a Fe/MgO/Mn3Sn MTJ and showed that the sign and direction of anisotropic longitudinal spin-polarized current in the antiferromagnet can be controlled by octupole direction. They measured a TMR ratio of around 2% at room temperature, which arises between the parallel and antiparallel configurations of the cluster magnetic octupoles in the chiral antiferromagnetic state. […]
Antiferromagnets are suitable for transporting spin waves over long distances, study finds
Phys.org December 6, 2022 In antiferromagnets, the efficient transport of spin-waves has until now only been observed in the insulating antiferromagnet hematite, where circularly polarized spin-waves diffuse over long distances. An international team of researchers (Germany, France, Norway, China) observed long-distance spin-transport in the antiferromagnetic orthoferrite YFeO3, where a different transport mechanism was enabled by the combined presence of the Dzyaloshinskii-Moriya interaction and externally applied fields. The magnon decay length exceeded hundreds of nanometers, in line with resonance measurements that highlight the low magnetic damping. They observed a strong anisotropy in the magnon decay lengths which they attributed to the […]
New data-decoding approach could lead to faster, smaller digital tech
Phys.org December 28, 2021 An international team of researchers (USA – University of Nebraska, University of Wisconsin, China) has shown that spin-independent conductance in compensated antiferromagnets and normal metals can be efficiently exploited in spintronics, provided their magnetic space group symmetry supports a non-spin-degenerate Fermi surface. Due to their momentum-dependent spin polarization, such antiferromagnets can be used as active elements in antiferromagnetic tunnel junctions (AFMTJs) and produce a giant tunneling magnetoresistance (TMR) effect. Using RuO2 as a representative compensated antiferromagnet exhibiting spin-independent conductance they designed a RuO2/TiO2/RuO2 (001) AFMTJ, where a globally spin-neutral charge current was controlled by the two […]
On the road to faster and more efficient data storage
Phys.org August 18, 2021 Antiferromagnet is a promising candidate for developing the next generation of information technology. An international team of researchers (Germany, Sweden, Japan, Italy) showed that domain walls play an active role in the dynamic properties of the antiferromagnet nickel oxide. The experiments revealed that magnetic waves with different frequencies could be induced, amplified, and even coupled with each other across different domains—but only in the presence of domain walls. The ability highlights the potential to actively control the propagation of magnetic waves in time and space as well as energy transfer among individual waves at the femtosecond […]
Researchers demonstrate the potential of a new quantum material for creating two spintronic technologies
Phys.org February 3, 2021 Finding materials with the exact characteristics necessary to fabricate Antiferromagnetic (AFM) spintronics has so far proved to be highly challenging. An international team of researchers (USA – UC Berkeley, Lawrence Berkeley National Laboratory, National High Magnetic Field Laboratory, UCLA, Israel) has identified a new quantum material (Fe1/3 + δNbS2) that could be used to fabricate AFM spintronic devices. They demonstrated that antiferromagnetic switching in the intercalated transition-metal dichalcogenide (TMD)-based compounds have a huge ‘exchange bias’, single-pulse saturation and a significantly lower activation energy. They showed that the coexistence of spin glass and antiferromagnetic order allows a […]
Researchers from NUS create ‘whirling’ nano-structures in anti-ferromagnets
EurekAlert February 4, 2021 Special magnetic nano-patterns in anti-ferromagnets that are shaped as whirls or vortices would be quite useful, as they are very stable structures and can potentially be moved along magnetic ‘race tracks’ at speeds of a few kilometres per second. To realize anti-ferromagnetic whirls an international team of researchers (Singapore, UK, USA – University of Wisconsin) combined high-quality film synthesis from materials engineering, phase transitions from physics and topology from mathematics. To grow these materials they fired a laser at iron-oxide. By using ultra-short pulses of laser, they created a hot vapour of atomic particles that formed […]
New devices could reduce excess heat in computers
Science Daily September 13, 2018 An international team of researchers (Germany, Norway, the Netherlands) demonstrated that antiferromagnetic iron oxide, which is the main component of rust, is a cheap and promising material to transport information with low excess heating at increased speeds. They used platinum wires on top of the insulating iron oxide to allow an electric current to pass close by. This electric current leads to a transfer of energy from the platinum into the iron oxide, thereby creating magnons. Antiferromagnets are unaffected by external magnetic fields, which is a key requirement for future data storage. Antiferromagnet-based devices can […]