Atomic-scale spin sensing of a 2D d-wave altermagnet via helical tunneling.

October 13, 2026| Source: Nature

Altermagnets simultaneously possess momentum-dependent nonrelativistic spin splitting and zero net magnetization (1-6). Their defining crystalline symmetry connects opposite-spin sublattices in real space and imposes alternating spin polarization on the symmetry-related electronic states in momentum space (1-3). Identifying such an order and its associated spin response therefore calls for atomic-scale spin-sensitive measurements in both real and momentum space, an experimental milestone yet to be achieved. Here we show that the helical edge modes of the higher-order topological insulator α-Bi 4 Br 4 can serve as a spin-selective scanning tunnelling microscopy probe of the two-dimensional d-wave altermagnetic order in the surface layer of KV 2 Se 2 O. Atomically registered mapping reveals the spatial relationship between the two V sublattices and a density-wave lattice modulation, as well as real-space patterns consistent with the checkerboard antiferromagnetic order. Field-dependent spectroscopy further finds opposite energy shifts of the unidirectional quasiparticle excitations extending along two orthogonal crystal axes and a predominantly out-of-plane magnetic response. In momentum space, spin-sensitive quasiparticle interference imaging reveals a bias-reversing d-wave anisotropy between the symmetry-paired X and Y valleys. These results provide converging evidence for two-dimensional d-wave altermagnetism on the surface of KV 2 Se 2 O and demonstrate helical-edge-mode tunnelling as a route for atomic-scale spin sensing in quantum materials.

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Nutrient legacies from elephant megacarcasses create coldspots of biodiversity and hotspots of ecosystem processes.

Terrestrial megafauna (animals >1,000 kg) have substantial impacts on ecosystems while alive; yet, we know little about the impacts of these ecosystem engineers after they die. Like whale carcasses in the ocean, terrestrial megacarcasses may leave ecological legacies via the nutrient pulses they create on the landscape. Here, we investigated the impact of elephant megacarcasses on savanna ecosystems in Kruger National Park, South Africa. To determine how elephant carcasses affect below- and a

EnvironmentOctober 20, 2026

Maternal ranging strategies facilitate offspring social play at energetic cost in the most solitary ape.

In most vertebrates, social play among peers is considered essential for behavioral development. Yet in solitary species bearing single offspring, opportunities for social play are inherently scarce. Whether mothers of such species actively facilitate play opportunities for their offspring, and at what cost, remains unknown. We used 15 y of behavioral and movement data (∼32,600 observation hours) from 31 wild Bornean orangutan ( Pongo pygmaeus wurmbii ) mother-offspring pairs to test whet

EnvironmentOctober 20, 2026

Evolution shapes ecosystem resilience through spatial self-organization.

Drylands are globally widespread and ecologically important but vulnerable to climate change. Many exhibit spatially self-organized vegetation patterns that enhance resilience by enabling vegetation to reorganize their patterns under drying, thereby optimizing water use and maintaining productivity. Plants can also undergo evolution in response to environmental change. Although both spatial self-organization and rapid evolution are fundamental mechanisms of resilience, their interaction remains

EnvironmentOctober 13, 2026

Continuous UV irradiation played an inconclusive role in selecting the canonical genetic alphabet.

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EnvironmentOctober 13, 2026

Fault-controlled natural hydrogen reservoirs as underground hydrogen storage sites.

Underground hydrogen storage requires geological formations with demonstrated hydrogen containment, yet no conventional storage candidate (salt caverns, aquifers, or depleted hydrocarbon reservoirs) offers direct, prior evidence of H 2 -specific sealing. We propose that subcommercial natural hydrogen reservoirs, where H 2 has accumulated over geological timescales, can serve as precertified storage sites. This proposition is evaluated using the Bulqizë fault-controlled natural H 2 reservoir