News

06.02.2024 "Science" acknowledges our work

We are proud to announce that the remarkable discovery of altermagnetism of our group and especially Libor Šmejkal are presented in an article from Science. The presence of a new magnetic class which might lead to fast eco-friendly electronic devices is reaching further interest in general science. This underlines the impact of our current research and will bring even more interest into the research field.

You can find the article here.

31.01.2024 New Joint Publication in Altermagnetism

A joint publication with Jairo Sinova, Libor Šmejkal and Anna Hellenes about the observation of time-reversal symmetry breaking in the band structure of altermagnetic RuO2 has been published in Science Advances.

They directly observe strong time-reversal symmetry breaking in the band structure of altermagnetic RuO2 by detecting magnetic circular dichroism in angle-resolved photoemission spectra. Their experimental results, supported by ab initio calculations, establish the microscopic electronic structure basis for a family of interesting phenomena and functionalities in fields ranging from topological matter to spintronics, which are based on the unconventional time-reversal symmetry breaking in altermagnets.

You can find the publication under Sci. Adv. 10, eadj4883 (2024).

29.01.2024 New Joint Publication in Altermagnetic Transport

A joint publication with Jairo Sinova and Libor Šmejkal about the crystal thermal transport in altermagnetic
RuO2 has been published in Physical Review Lettters.

They demonstrate the emergence of a pronounced thermal transport in the recently discovered class of magnetic materials—altermagnets. From symmetry arguments and first-principles calculations performed for the showcase altermagnet, RuO2, they uncover that crystal Nernst and crystal thermal Hall effects in this material are very large and strongly anisotropic with respect to the Néel vector. They find the large crystal thermal transport to originate from three sources of Berry’s curvature in momentum space: the Weyl fermions due to crossings between well-separated bands, the strong spin-flip pseudonodal surfaces, and the weak spin-flip ladder transitions, defined by transitions among very weakly spin-split states of similar dispersion crossing the Fermi surface. Moreover, they reveal that the anomalous thermal and electrical transport coefficients in RuO2 are linked by an extended Wiedemann-Franz law in a temperature range much wider than expected for conventional magnets. Their results suggest that altermagnets may assume a leading role in realizing concepts in spin caloritronics not achievable with ferromagnets or antiferromagnets.

You can find the publication under Phys. Rev. Lett. 132, 056701 (2024).

27.01.2024 New Joint Publication in Antiferromagnetic Spintronics

A joint publication with Jairo Sinova, Libor Šmejkal and Helen Gomonay about phase transitions associated with magnetic-field induced topological orbital momenta in a non-collinear antiferromagnet has been published in Nature communications.

They show that in polycrystalline Mn3Zn0.5Ge0.5N with non-collinear antiferromagnetic order, changes in the diagonal and, rather unexpected, off-diagonal components of the resistivity tensor occur at low temperatures indicating subtle transitions between magnetic phases of different symmetry. This is supported by neutron scattering and explained within a phenomenological model which suggests that the phase transitions in magnetic field are associated with field induced topological orbital momenta. The fact that they observe transitions between spin phases in a polycrystal, where effects of crystalline anisotropy are cancelled suggests that they are only controlled by exchange interactions. The observation of an off-diagonal resistivity extends the possibilities for realising antiferromagnetic spintronics with polycrystalline materials.

You can find the publication under Nat. Comm. 15, 822 (2024).

24.01.2024 The Economist acknowledges our work

We are proud to announce that the remarkable discovery of altermagnetism of our group and especially Libor Šmejkal are presented in an article from The Economist. The presence of a new magnetic class which might lead to fast eco-friendly electronic devices is reaching interest outside of science. This underlines the impact of our current research and will bring even more interest into the research field.

You can find the article here.

18.01.2024 New Publication in Altermagnetism

A joint publication with Libor Šmejkal about the broken Kramers degeneracy in altermagnetic MnTe has been published in Physical Review Letters.

By combining high-quality film growth and in situ angle-resolved photoemission spectroscopy, they report the electronic structure of an altermagnetic candidate, αMnTe. Temperature-dependent study reveals the lifting of Kramers degeneracy accompanied by a magnetic phase transition at TN=267Kwith spin splitting of up to 370 meV, providing direct spectroscopic evidence for altermagnetism in MnTe.

You can find the publication under Phys. Rev. Lett. 132, 036702 (2024).

20.12.2023 New Joint Publication in Altermagnetic Magnonics

A joint publication with Jairo Sinova and Libor Šmejkal about crystal magnons in altermagnets has been published in Physical Review Letters.

They theoretically demonstrate a new class of magnons on a prototypical d-wave altermagnet
RuO2 with the compensated antiparallel magnetic order in the ground state. Based on density-functional-theory calculations they observe that the THz-range magnon bands in RuO2 have an alternating chirality splitting, similar to the alternating spin splitting of the electronic bands, and a linear magnon dispersion near the zero wave vector. They also show that, overall, the Landau damping of this metallic altermagnet is suppressed due to the spin-split electronic structure, as compared to an artificial antiferromagnetic phase of the same RuO2 crystal with spin-degenerate electronic bands and chirality-degenerate magnon bands.

You can find the publication under Phys. Rev. Lett. 131, 256703 (2023).

08.12.2023 New Publication in Antiferromagnetic Transport Theory

A joint publication with Libor Šmejkal and Rafeal González-Hernández about the Anomalous Hall Effect in in doped AgCrSe2 has been published in Advanced Science.

They report the observation of a spontaneous AHE in doped AgCrSe2, a layered polar semiconductor with an antiferromagnetic coupling between Cr spins in adjacent layers. The anomalous Hall resistivity is comparable to the largest observed in compensated magnetic systems to date, and is rapidly switched off when the angle of an applied magnetic field is rotated to ≈80° from the crystalline c-axis. The ionic gating experiments show that the anomalous Hall conductivity magnitude can be enhanced by modulating the p-type carrier density. They also present theoretical results that suggest the AHE is driven by Berry curvature due to noncollinear antiferromagnetic correlations among Cr spins, which are consistent with the previously suggested magnetic ordering in AgCrSe2. Their results open the possibility to study the interplay of magnetic and ferroelectric-like responses in this fascinating class of materials.

You can find the publication under Adv. Sci. 2023, 2307306 (2023).

04.12.2023 New Joint Publication in Topological Altermagnetism

A joint publication with Jairo Sinova and Libor Šmejkal about the influence of magnetism, strain, and pressure on the band topology of EuCd2As2 has been published in Physical Review B.

They analyze the role of the delicate interplay of Eu magnetism, strain, and pressure on the realization of nontrivial topological phases. For that they invoke a combination of a group theoretical analysis with ab initio density functional theory calculations and uncover a rich phase diagram with various nontrivial topological phases beyond a Weyl semimetallic state, such as axion and topological crystalline insulating phases, and discuss their realization.

You can find the publication under Phys. Rev. B 108, 235113 (2023).

09.11.2023 Libor Šmejkal wins the "Falling Walls Science Breakthrough of the Year 2023" award in physical sciences

Congratulations to Libor Šmejkal for winning the Falling Walls Science Breakthrough of the Year 2023 award in physical sciences.

In the Falling Walls science summit the brightest minds in science, politics, business and the media come together to present groundbreaking discoveries and scientific breakthroughs and emerging trends that shape our world. Libor was awarded for his his breakthrough of altermagnets—a discovery that has the potential to revolutionise the way we design and use electronic technology, making it much more efficient and sustainable.