Physical Review Materials

We show that the shape of a finite altermagnetic sample can generate a measurable spin polarization, even though these materials exhibit zero net magnetization in the large-system limit. This effect arises from the interplay between anisotropic spin-resolved band structures and the discrete set of allowed electron states in confined geometries. For rectangular samples, unequal dimensions lead to an imbalance between spin populations. We propose transport-based probes to detect this geometry-induced spin polarization, which manifests as characteristic signatures in magnetoresistance. Our results reveal a simple and robust route to controlling spin using sample geometry alone, opening new possibilities for nanoscale spintronic devices based on altermagnets.

Altermagnetism is reshaping fundamental understanding of magnetism, combining zero net magnetization with spin-split electronic bands, all without needing heavy, expensive elements. But how to find these materials efficiently? The authors performed a high-throughput screening of the MAGNDATA database (2287 experimentally characterized magnetic structures) by combining symmetry analysis with spin-polarized DFT. This identified 180 robust altermagnets, both metallic and semiconducting, many previously unreported. Representative cases such as UCr2Si2C, NbMnP, and YRuO3 exhibit particularly large splittings. The authors’ open-access database (https://altermagnets.anyterial.se/) provides full results, and momentum-resolved analysis shows that maximal splitting often occurs away from conventional high-symmetry paths, directly guides future ARPES experiments.

The authors demonstrate the coexistence of $d$-wave altermagnetism and nontrivial band topology in Janus FeSe$X$ ($X$ = S, Te) monolayers. In the nonrelativistic limit, the two-dimensional system exhibits momentum-dependent spin splitting with vanishing net magnetization, a signature of $d$-wave altermagnetic order. Upon inclusion of spin–orbit coupling, a topological gap opens, accompanied by symmetry-protected, spin-polarized edge states. The intrinsic interplay between altermagnetic order and relativistic effects enables robust, low-dissipation spin transport, establishing Janus FeSeX as a compelling platform for next-generation quantum applications.

The search for altermagnetic and related materials has largely focused on ideal crystals, overlooking the role of short-range chemical order. Using density functional theory and a cluster expansion model, the authors show that short-range anion correlations in iron oxyfluoride (FeOF) tune the magnitude and character of nonrelativistic spin splitting, producing splittings absent in ordered FeF${}_2$ and virtual-crystal approximation models. The authors further identify magneto-optical Kerr spectroscopy as a route to detect these effects experimentally and highlight heteroanionic substitution as a design strategy for high-$T_N$ spin-split antiferromagnets.

As a material that undergoes a metal-insulator transition inside the altermagnetic phase, NiS${}_{2-x}$Se${}_x$ provides an ideal framework to elucidate the interplay between electronic correlations and altermagnetism. This work disentangles the impact of static and dynamic correlations on altermagnetic properties by systematically comparing DFT, DFT+$U$, and DFT+DMFT calculations on NiS${}_{2-x}$Se${}_x$. The key result is that dynamical correlations not only modify the magnitude of the spin splitting but also promote a sharp asymmetry in the lifetimes of spin-up and spin-down quasiparticles, which is further amplified by multi-orbital Hund’s correlation effects.

Wurtzite Mn$X$ ($X$ = S, Se, Te) is predicted to host multiferroic antiferromagnetic (AFM) phases featuring switchable ferroelectric polarization, with altermagnetism emerging upon Cr doping. First-principles and spin-model calculations reveal a frustrated stripe AFM ground state in pristine compounds, while Cr doping drives a transition to an A-type AFM phase exhibiting $g$-wave altermagnetism with large nonrelativistic spin splitting. Remarkably, polarization reversal switches the spin splitting without rotating the Néel vector. Distinct magnetic phases yield symmetry-selective linear and nonlinear Hall responses, providing clear transport fingerprints and establishing doped MnX as a platform for electrically controlled AFM spintronics.

Altermagnons are collective spin excitations in altermagnets, characterized by anisotropic magnon dispersions. The altermagnet CrSb has emerged as a compelling material owing to its substantial spin-splitting energy. Here, the authors report on the growth of high-quality CrSb single crystals and investigate their thermodynamic and transport properties. A large positive magnetoresistance of nearly 80% is observed at 3.5 K. Interestingly, the room-temperature specific heat exceeds the Dulong-Petit limit, attributed to a broad altermagnon contribution with an energy gap of ~16 ± 1 meV. These findings highlight the potential of CrSb for room-temperature magnonic and spintronic applications.

Excitation by linearly polarized femtosecond laser pulses provides a direct view into the altermagnetic structure via the non-equilibrium spin-polarized electronic populations in a band structure whose symmetry encodes the underlying bulk g-wave order. The spin-dependent electronic response calculated in this paper can be accessed by optical pump-probe experiments. The authors show that, surprisingly, such a purely optical technique reveals planar d-wave- and g-wave-like signatures hidden within the three-dimensional bulk g-wave spin-order configuration. Crucially, the symmetry properties of the calculated response can be well approximated by using two-dimensional “spin cuts”, which enable a transparent interpretation of the optical response and motivate concrete magneto-optical pump-probe configurations for bulk altermagnets.