Browsing by Author "Valvidares, Manuel"
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- ItemAuthor Correction: Ultrafast X-ray imaging of the light-induced phase transition in VO2 (Nature Physics, (2022), 10.1038/s41567-022-01848-w)(Basingstoke : Nature Publishing Group, 2023) Johnson, Allan S.; Perez-Salinas, Daniel; Siddiqui, Khalid M.; Kim, Sungwon; Choi, Sungwook; Volckaert, Klara; Majchrzak, Paulina E.; Ulstrup, Søren; Agarwal, Naman; Hallman, Kent; Haglund, Richard F.; Günther, Christian M.; Pfau, Bastian; Eisebitt, Stefan; Backes, Dirk; Maccherozzi, Francesco; Fitzpatrick, Ann; Dhesi, Sarnjeet S.; Gargiani, Pierluigi; Valvidares, Manuel; Artrith, Nongnuch; de Groot, Frank; Choi, Hyeongi; Jang, Dogeun; Katoch, Abhishek; Kwon, Soonnam; Park, Sang Han; Kim, Hyunjung; Wall, Simon E.In the version of this article initially published, the Acknowledgements was missing thanks from Soonnam Kwon for support from the National Research Foundation of Korea (NRF-2020R1A2C1007416). The error has been corrected in the HTML and PDF versions of the article.
- ItemIntermixing-Driven Surface and Bulk Ferromagnetism in the Quantum Anomalous Hall Candidate MnBi6Te10(Weinheim : Wiley-VCH, 2023) Tcakaev, Abdul‐Vakhab; Rubrecht, Bastian; Facio, Jorge I.; Zabolotnyy, Volodymyr B.; Corredor, Laura T.; Folkers, Laura C.; Kochetkova, Ekaterina; Peixoto, Thiago R. F.; Kagerer, Philipp; Heinze, Simon; Bentmann, Hendrik; Green, Robert J.; Gargiani, Pierluigi; Valvidares, Manuel; Weschke, Eugen; Haverkort, Maurits W.; Reinert, Friedrich; van den Brink, Jeroen; Büchner, Bernd; Wolter, Anja U. B.; Isaeva, Anna; Hinkov, VladimirThe recent realizations of the quantum anomalous Hall effect (QAHE) in MnBi2Te4 and MnBi4Te7 benchmark the (MnBi2Te4)(Bi2Te3)n family as a promising hotbed for further QAHE improvements. The family owes its potential to its ferromagnetically (FM) ordered MnBi2Te4 septuple layers (SLs). However, the QAHE realization is complicated in MnBi2Te4 and MnBi4Te7 due to the substantial antiferromagnetic (AFM) coupling between the SLs. An FM state, advantageous for the QAHE, can be stabilized by interlacing the SLs with an increasing number n of Bi2Te3 quintuple layers (QLs). However, the mechanisms driving the FM state and the number of necessary QLs are not understood, and the surface magnetism remains obscure. Here, robust FM properties in MnBi6Te10 (n = 2) with Tc ≈ 12 K are demonstrated and their origin is established in the Mn/Bi intermixing phenomenon by a combined experimental and theoretical study. The measurements reveal a magnetically intact surface with a large magnetic moment, and with FM properties similar to the bulk. This investigation thus consolidates the MnBi6Te10 system as perspective for the QAHE at elevated temperatures.
- ItemLarge-area van der Waals epitaxy and magnetic characterization of Fe3GeTe2 films on graphene(Bristol : IOP Publ., 2021) Lopes, J. Marcelo J.; Czubak, Dietmar; Zallo, Eugenio; Figueroa, Adriana I.; Guillemard, Charles; Valvidares, Manuel; Rubio-Zuazo, Juan; López-Sanchéz, Jesús; Valenzuela, Sergio O.; Hanke, Michael; Ramsteiner, ManfredScalable fabrication of magnetic 2D materials and heterostructures constitutes a crucial step for scaling down current spintronic devices and the development of novel spintronic applications. Here, we report on van der Waals (vdW) epitaxy of the layered magnetic metal Fe3GeTe2 (FGT) - a 2D crystal with highly tunable properties and a high prospect for room temperature ferromagnetism (FM) - directly on graphene by employing molecular beam epitaxy. Morphological and structural characterization confirmed the realization of large-area, continuous FGT/graphene heterostructure films with stable interfaces and good crystalline quality. Furthermore, magneto-transport and x-ray magnetic circular dichroism investigations confirmed a robust out-of-plane FM in the layers, comparable to state-of-the-art exfoliated flakes from bulk crystals. These results are highly relevant for further research on wafer-scale growth of vdW heterostructures combining FGT with other layered crystals such as transition metal dichalcogenides for the realization of multifunctional, atomically thin devices. © 2021 The Author(s).
- ItemA New Highly Anisotropic Rh-Based Heusler Compound for Magnetic Recording(Weinheim : Wiley-VCH, 2020) He, Yangkun; Fecher, Gerhard H.; Fu, Chenguang; Pan, Yu; Manna, Kaustuv; Kroder, Johannes; Jha, Ajay; Wang, Xiao; Hu, Zhiwei; Agrestini, Stefano; Herrero-Martín, Javier; Valvidares, Manuel; Skourski, Yurii; Schnelle, Walter; Stamenov, Plamen; Borrmann, Horst; Tjeng, Liu Hao; Schaefer, Rudolf; Parkin, Stuart S.P.; Coey, John Michael D.; Felser, ClaudiaThe development of high-density magnetic recording media is limited by superparamagnetism in very small ferromagnetic crystals. Hard magnetic materials with strong perpendicular anisotropy offer stability and high recording density. To overcome the difficulty of writing media with a large coercivity, heat-assisted magnetic recording was developed, rapidly heating the media to the Curie temperature Tc before writing, followed by rapid cooling. Requirements are a suitable Tc, coupled with anisotropic thermal conductivity and hard magnetic properties. Here, Rh2CoSb is introduced as a new hard magnet with potential for thin-film magnetic recording. A magnetocrystalline anisotropy of 3.6 MJ m−3 is combined with a saturation magnetization of μ0Ms = 0.52 T at 2 K (2.2 MJ m−3 and 0.44 T at room temperature). The magnetic hardness parameter of 3.7 at room temperature is the highest observed for any rare-earth-free hard magnet. The anisotropy is related to an unquenched orbital moment of 0.42 μB on Co, which is hybridized with neighboring Rh atoms with a large spin–orbit interaction. Moreover, the pronounced temperature dependence of the anisotropy that follows from its Tc of 450 K, together with a thermal conductivity of 20 W m−1 K−1, make Rh2CoSb a candidate for the development of heat-assisted writing with a recording density in excess of 10 Tb in.−2. © 2020 The Authors. Published by Wiley-VCH GmbH
- ItemRobust Single Molecule Magnet Monolayers on Graphene and Graphite with Magnetic Hysteresis up to 28 K(Weinheim : Wiley-VCH, 2021) Spree, Lukas; Liu, Fupin; Neu, Volker; Rosenkranz, Marco; Velkos, Georgios; Wang, Yaofeng; Schiemenz, Sandra; Dreiser, Jan; Gargiani, Pierluigi; Valvidares, Manuel; Chen, Chia-Hsiang; Büchner, Bernd; Avdoshenko, Stanislav M.; Popov, Alexey A.The chemical functionalization of fullerene single molecule magnet Tb2@C80(CH2Ph) enables the facile preparation of robust monolayers on graphene and highly oriented pyrolytic graphite from solution without impairing their magnetic properties. Monolayers of endohedral fullerene functionalized with pyrene exhibit magnetic bistability up to a temperature of 28 K. The use of pyrene terminated linker molecules opens the way to devise integration of spin carrying units encapsulated by fullerene cages on graphitic substrates, be it single-molecule magnets or qubit candidates. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH