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Université de Fribourg

Infrared study of the multiband low-energy excitations of the topological antiferromagnet MnBi2Te4

Xu, Bing ; Zhang, Y. ; Alizade, E. H. ; Jahangirli, Z. A. ; Lyzwa, Fryderyk ; Sheveleva, Evgeniia ; Marsik, Premysl ; Li, Y. K. ; Yao, Y. G. ; Wang, Z. W. ; Shen, B. ; Dai, Y. M. ; Kataev, V. ; Otrokov, M. M. ; Chulkov, E. V. ; Mamedov, N. T. ; Bernhard, Christian

In: Physical Review B, 2021, vol. 103, no. 12, p. L121103

With infrared spectroscopy, we studied the bulk electronic properties of the topological antiferromagnet MnBi2Te4 with TN ≃ 25 K. With the support of band-structure calculations, we assign the intra- and interband excitations and determine the band gap of Eg ≈ 0.17 eV. We also obtain evidence for two types of conduction bands with light and very heavy carriers. The multiband free-carrier...

Université de Fribourg

${\eta}$-paired superconducting hidden phase in photodoped Mott insulators

Li, Jiajun ; Golez, Denis ; Werner, Philipp ; Eckstein, Martin

In: Physical Review B, 2020, vol. 102, no. 16, p. 165136

We show that a metastable η-pairing superconducting phase can be induced by photodoping doublons and holes into a strongly repulsive fermionic Hubbard model. The doublon-hole condensate originates from an intrinsic doublon-hole exchange interaction and does not rely on the symmetry of the half-filled Hubbard model. It extends over a wide range of doublon densities and effective temperatures....

Université de Fribourg

Alpha‐synuclein dopaminylation presented in plasma of both healthy subjects and parkinson’s disease patients

Zhao, Huiyuan ; Huang, Shuai ; Palanisamy, Sivakumar ; Wang, Cui ; Rainer, Gregor ; Zhang, Xiaozhe

In: PROTEOMICS – Clinical Applications, 2020, vol. 14, no. 5, p. 1900117

Alpha‐synuclein (α‐syn) dopaminylation can lead to the death of dopaminergic neurons in the brain and is a risk factor of Parkinson's disease (PD). This study aims to examine whether such a posttranslational modification (PTM) is presented in human blood plasma. Experimental Design: In vitro reaction simulation between α‐syn and dopamine (DA) is conducted to study the biochemical...

Université de Fribourg

Cenozoic evolution of the steppe-desert biome in Central Asia

Barbolini, N. ; Woutersen, A. ; Dupont-Nivet, G. ; Silvestro, Daniele ; Tardif, D. ; Coster, P. M. C. ; Meijer, N. ; Chang, C. ; Zhang, H.-X. ; Licht, A. ; Rydin, C. ; Koutsodendris, A. ; Han, F. ; Rohrmann, A. ; Liu, X.-J. ; Zhang, Y. ; Donnadieu, Y. ; Fluteau, F. ; Ladant, J.-B. ; Le Hir, G. ; Hoorn, C.

In: Science Advances, 2020, vol. 6, no. 41, p. eabb8227

The origins and development of the arid and highly seasonal steppe-desert biome in Central Asia, the largest of its kind in the world, remain largely unconstrained by existing records. It is unclear how Cenozoic climatic, geological, and biological forces, acting at diverse spatial and temporal scales, shaped Central Asian ecosystems through time. Our synthesis shows that the Central Asian...

Université de Fribourg

Shining a light on species delimitation in the tree genus Engelhardia Leschenault ex Blume (Juglandaceae)

Zhang, Can-Yu ; Low, Shook Ling ; Song, Yi-Gang ; Nuraina ; Kozlowski, Gregor ; Do, Truong Van ; Li, Lang ; Zhou, Shi-Shun ; Tan, Yun-Hong ; Cao, Guan-Long ; Zhou, Zhuo ; Meng, Hong-Hu ; Li, Jie

In: Molecular Phylogenetics and Evolution, 2020, vol. 152, p. 106918

Enhanced efficacy in species delimitation is critically important in biology given the pending biodiversity crisis under global warming and anthropogenic activity. In particular, delineation of traditional classifications in view of the complexity of species requires an integrative approach to effectively define species boundaries, and this is a major focus of systematic biology. Here, we...

Université de Fribourg

Mapping the unoccupied state dispersions in ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$ with resonant inelastic x-ray scattering

Monney, Claude ; Herzog, Marc ; Pulkkinen, Aki ; Huang, Y. ; Pelliciari, Jonathan ; Olalde-Velasco, P. ; Katayama, Naoyuk ; Nohara, Minoru ; Takagi, Hide ; Schmitt, Thorsten ; Mizokawa, Takashi

In: Physical Review B, 2020, vol. 102, no. 8, p. 085148

The transition metal chalcogenide Ta2NiSe5 undergoes a second-order phase transition at Tc=328K involving a small lattice distortion. Below Tc, a band gap at the center of its Brillouin zone increases up to about 0.35 eV. In this work, we study the electronic structure of Ta2NiSe5 in its low-temperature semiconducting phase, using resonant inelastic x-ray scattering (RIXS) at the Ni L3 edge....

Université de Fribourg

Analysis method for detecting topological defect dark matter with a global magnetometer network

Masia-Roig, Hector ; A.Smiga, Joseph ; Budker, Dmitry ; Dumont, Vincent ; Gruji, Zoran ; Kim, Dongok ; Kimball, Derek F. Jackson ; Lebedev, Victor ; Monroy, Madeline ; Pustelny, Szymon ; Scholtes, Theo ; Segura, Perrin C. ; Semertzidi, Yannis K. ; Shin, Yun Chang ; Stalnaker, Jason E. ; Sulai, Ibrahim ; Weis, Antoine ; Wickenbrock, Arne

In: Physics of the Dark Universe, 2020, vol. 28, p. 100494

The Global Network of Optical Magnetometers for Exotic physics searches (GNOME) is a network of time-synchronized, geographically separated, optically pumped atomic magnetometers that is being used to search for correlated transient signals heralding exotic physics. GNOME is sensitive to exotic couplings of atomic spins to certain classes of dark matter candidates, such as axions. This work...

Université de Fribourg

Global biogeographic synthesis and priority conservation regions of the relict tree family Juglandaceae

Song, Yi‐Gang ; Fragnière, Yann ; Meng, Hong‐Hu ; Li, Ying ; Bétrisey, Sébastien ; Corrales, Adriana ; Manchester, Steven ; Deng, Min ; Jasińska, Anna K. ; Văn Sâm, Hoàng ; Kozlowski, Gregor

In: Journal of Biogeography, 2020, vol. 47, no. 3, p. 643–657

Aim To establish a complete database of Juglandaceae at a spatiotemporal scale and develop a phylogeographic framework with which to elucidate the distributional patterns, diversity patterns, origins, evolution, and conservation priority regions of this family. Location Worldwide. Taxon Walnut family (Juglandaceae). Methods Data on the distribution of all the extant and fossil species of...

Université de Fribourg

Structural insights into the EGO-TC–mediated membrane tethering of the TORC1-regulatory Rag GTPases

Zhang, Tianlong ; Péli-Gulli, Marie-Pierre ; Zhang, Zhen ; Tang, Xin ; Ye, Jie ; Virgilio, Claudio De ; Ding, Jianping

In: Science Advances, 2019, vol. 5, no. 9, p. eaax8164

The Rag/Gtr GTPases serve as a central module in the nutrient-sensing signaling network upstream of TORC1. In yeast, the anchoring of Gtr1-Gtr2 to membranes depends on the Ego1-Ego2-Ego3 ternary complex (EGO-TC), resulting in an EGO- TC-Gtr1-Gtr2 complex (EGOC). EGO-TC and human Ragulator share no obvious sequence similarities and also differ in their composition with respect to the number of ...

Université de Fribourg

Revealing ‘plasmaron’ feature in DySb by optical spectroscopy study

Ban, W J ; Wu, D S ; Xu, Bing ; Luo, J L ; Xiao, Hong

In: Journal of Physics: Condensed Matter, 2019, vol. 31, no. 40, p. 405701

We report magnetic susceptibility, resistivity and optical spectroscopy study on single crystal sample DySb. It exhibits extremely large magnetoresistance (XMR), and a magnetic phase transition from paramagnetic (PM) to antiferromagnetic (AFM) state at about 10 K. A 'screened' plasma edge at about 4000 cm−1 is revealed by optical measurement, which suggests that the material has a low...