Previous Issue
Volume 5, June
 
 

Magnetism, Volume 5, Issue 3 (September 2025) – 4 articles

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Select all
Export citation of selected articles as:
22 pages, 6376 KiB  
Article
Components for an Inexpensive CW-ODMR NV-Based Magnetometer
by André Bülau, Daniela Walter and Karl-Peter Fritz
Magnetism 2025, 5(3), 18; https://doi.org/10.3390/magnetism5030018 - 1 Aug 2025
Viewed by 799
Abstract
Quantum sensing based on NV-centers in diamonds has been demonstrated many times in multiple publications. The majority of publications use lasers in free space or lasers with fiber optics, expensive optical components such as dichroic mirrors, or beam splitters with dichroic filters and [...] Read more.
Quantum sensing based on NV-centers in diamonds has been demonstrated many times in multiple publications. The majority of publications use lasers in free space or lasers with fiber optics, expensive optical components such as dichroic mirrors, or beam splitters with dichroic filters and expensive detectors, such as Avalanche photodiodes or single photon detectors, overall, leading to custom and expensive setups. In order to provide an inexpensive NV-based magnetometer setup for educational use in schools, to teach the three topics, fluorescence, optically detected magnetic resonance, and Zeeman splitting, inexpensive, miniaturized, off-the-shelf components with high reliability have to be used. The cheaper such a setup, the more setups a school can afford. Hence, in this work, we investigated LEDs as light sources, considered different diamonds for our setup, tested different color filters, proposed an inexpensive microwave resonator, and used a cheap photodiode with an appropriate transimpedance amplifier as the basis for our quantum magnetometer. As a result, we identified cheap and functional components and present a setup and show that it can demonstrate the three topics mentioned at a hardware cost <EUR 100. Full article
Show Figures

Figure 1

26 pages, 38696 KiB  
Review
Altermagnetism and Altermagnets: A Brief Review
by Rupam Tamang, Shivraj Gurung, Dibya Prakash Rai, Samy Brahimi and Samir Lounis
Magnetism 2025, 5(3), 17; https://doi.org/10.3390/magnetism5030017 - 23 Jul 2025
Viewed by 1818
Abstract
Recently, a new class of magnetic material, termed altermagnets, has caught the attention of the magnetism and spintronics community. The magnetic phenomenon arising from these materials differs from traditional ferromagnetism and antiferromagnetism. It generally lacks net magnetization and is characterized by unusual non-relativistic [...] Read more.
Recently, a new class of magnetic material, termed altermagnets, has caught the attention of the magnetism and spintronics community. The magnetic phenomenon arising from these materials differs from traditional ferromagnetism and antiferromagnetism. It generally lacks net magnetization and is characterized by unusual non-relativistic spin-splitting and broken time-reversal symmetry. This leads to novel transport properties, such as the anomalous Hall effect, the crystal Nernst effect, and spin-dependent phenomena. Spin-dependent phenomena such as spin currents, spin-splitter torques, and high-frequency dynamics emerge as key characteristics in altermagnets. This paper reviews the main aspects pertaining to altermagnets by providing an overview of theoretical investigations and experimental realizations. We discuss the most recent developments in altermagnetism and prospects for exploiting its unique properties in next-generation devices. Full article
Show Figures

Figure 1

23 pages, 816 KiB  
Article
Large Angular Momentum
by Kenichi Konishi and Roberto Menta
Magnetism 2025, 5(3), 16; https://doi.org/10.3390/magnetism5030016 - 9 Jul 2025
Viewed by 454
Abstract
The quantum states of a spin 12 (a qubit) are parametrized by the space CP1S2, the Bloch sphere. A spin j for a generic j (a 2j+1-state system) is represented instead by a [...] Read more.
The quantum states of a spin 12 (a qubit) are parametrized by the space CP1S2, the Bloch sphere. A spin j for a generic j (a 2j+1-state system) is represented instead by a point in a larger space, CP2j. Here we study the state of a single angular momentum/spin in the limit j. A special class of states, |j,nCP2j, with spin oriented towards definite spatial directions, nS2, i.e., (J^·n)|j,n=j|j,n, are found to behave as classical angular momenta, jn, in this limit. Vice versa, general spin states in CP2j do not become classical, even at a large j. We study these questions by analyzing the Stern–Gerlach processes, the angular momentum composition rule, and the rotation matrix. Our observations help to better clarify how classical mechanics emerges from quantum mechanics in this context (e.g., with the unique trajectories of a particle carrying a large spin in an inhomogeneous magnetic field) and to make the widespread idea that large spins somehow become classical more precise. Full article
Show Figures

Figure 1

15 pages, 689 KiB  
Article
Magnetic Toroidal Monopole in a Single-Site System
by Satoru Hayami
Magnetism 2025, 5(3), 15; https://doi.org/10.3390/magnetism5030015 - 25 Jun 2025
Viewed by 413
Abstract
A magnetic toroidal monopole, which characterizes time-reversal-odd polar-charge quantity, manifests itself not only in antiferromagnetism but also in time-reversal switching physical responses. We theoretically investigate an atomic-scale description of the magnetic toroidal monopole based on multipole representation theory, which consists of four types [...] Read more.
A magnetic toroidal monopole, which characterizes time-reversal-odd polar-charge quantity, manifests itself not only in antiferromagnetism but also in time-reversal switching physical responses. We theoretically investigate an atomic-scale description of the magnetic toroidal monopole based on multipole representation theory, which consists of four types of multipoles. We show that the magnetic toroidal monopole degree of freedom is activated as the off-diagonal imaginary hybridization between the single-site orbitals with the same orbital angular momentum but different principal quantum numbers. We demonstrate that the expectation value of the magnetic toroidal monopole becomes nonzero when both electric and magnetic fields are applied to the system. Full article
Show Figures

Figure 1

Previous Issue
Back to TopTop