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Electrical manipulation of a topological antiferromagnetic state 期刊论文
NATURE, 2020, 580 (7805) : 608-+
作者:  Chabon, Jacob J.;  Hamilton, Emily G.;  Kurtz, David M.;  Esfahani, Mohammad S.;  Moding, Everett J.;  Stehr, Henning;  Schroers-Martin, Joseph;  Nabet, Barzin Y.;  Chen, Binbin;  Chaudhuri, Aadel A.;  Liu, Chih Long;  Hui, Angela B.;  Jin, Michael C.;  Azad, Tej D.;  Almanza, Diego;  Jeon, Young-Jun;  Nesselbush, Monica C.;  Keh, Lyron Co Ting;  Bonilla, Rene F.;  Yoo, Christopher H.;  Ko, Ryan B.;  Chen, Emily L.;  Merriott, David J.;  Massion, Pierre P.;  Mansfield, Aaron S.;  Jen, Jin;  Ren, Hong Z.;  Lin, Steven H.;  Costantino, Christina L.;  Burr, Risa;  Tibshirani, Robert;  Gambhir, Sanjiv S.;  Berry, Gerald J.;  Jensen, Kristin C.;  West, Robert B.;  Neal, Joel W.;  Wakelee, Heather A.;  Loo, Billy W., Jr.;  Kunder, Christian A.;  Leung, Ann N.;  Lui, Natalie S.;  Berry, Mark F.;  Shrager, Joseph B.;  Nair, Viswam S.;  Haber, Daniel A.;  Sequist, Lecia V.;  Alizadeh, Ash A.;  Diehn, Maximilian
收藏  |  浏览/下载:36/0  |  提交时间:2020/07/03

Room-temperature electrical switching of a topological antiferromagnetic state in polycrystalline Mn3Sn thin films is demonstrated using the same protocol as that used for conventional ferromagnetic metals.


Electrical manipulation of phenomena generated by nontrivial band topology is essential for the development of next-generation technology using topological protection. A Weyl semimetal is a three-dimensional gapless system that hosts Weyl fermions as low-energy quasiparticles(1-4). It has various exotic properties, such as a large anomalous Hall effect (AHE) and chiral anomaly, which are robust owing to the topologically protected Weyl nodes(1-16). To manipulate such phenomena, a magnetic version of Weyl semimetals would be useful for controlling the locations of Weyl nodes in the Brillouin zone. Moreover, electrical manipulation of antiferromagnetic Weyl metals would facilitate the use of antiferromagnetic spintronics to realize high-density devices with ultrafast operation(17,18). However, electrical control of a Weyl metal has not yet been reported. Here we demonstrate the electrical switching of a topological antiferromagnetic state and its detection by the AHE at room temperature in a polycrystalline thin film(19) of the antiferromagnetic Weyl metal Mn3Sn9,10,12,20, which exhibits zero-field AHE. Using bilayer devices composed of Mn3Sn and nonmagnetic metals, we find that an electrical current density of about 10(10) to 10(11) amperes per square metre induces magnetic switching in the nonmagnetic metals, with a large change in Hall voltage. In addition, the current polarity along the bias field and the sign of the spin Hall angle of the nonmagnetic metals-positive for Pt (ref. (21)), close to 0 for Cu and negative for W (ref. (22))-determines the sign of the Hall voltage. Notably, the electrical switching in the antiferromagnet is achieved with the same protocol as that used for ferromagnetic metals(23,24). Our results may lead to further scientific and technological advances in topological magnetism and antiferromagnetic spintronics.


  
Spontaneous gyrotropic electronic order in a transition-metal dichalcogenide 期刊论文
NATURE, 2020, 578 (7796) : 545-+
作者:  Kum, Hyun S.;  Lee, Hyungwoo;  Kim, Sungkyu;  Lindemann, Shane;  Kong, Wei;  Qiao, Kuan;  Chen, Peng;  Irwin, Julian;  Lee, June Hyuk;  Xie, Saien;  Subramanian, Shruti;  Shim, Jaewoo;  Bae, Sang-Hoon;  Choi, Chanyeol;  Ranno, Luigi;  Seo, Seungju;  Lee, Sangho;  Bauer, Jackson;  Li, Huashan;  Lee, Kyusang;  Robinson, Joshua A.;  Ross, Caroline A.;  Schlom, Darrell G.;  Rzchowski, Mark S.;  Eom, Chang-Beom;  Kim, Jeehwan
收藏  |  浏览/下载:10/0  |  提交时间:2020/07/03

Chirality is ubiquitous in nature, and populations of opposite chiralities are surprisingly asymmetric at fundamental levels(1,2). Examples range from parity violation in the subatomic weak force to homochirality in biomolecules. The ability to achieve chirality-selective synthesis (chiral induction) is of great importance in stereochemistry, molecular biology and pharmacology(2). In condensed matter physics, a crystalline electronic system is geometrically chiral when it lacks mirror planes, space-inversion centres or rotoinversion axes(1). Typically, geometrical chirality is predefined by the chiral lattice structure of a material, which is fixed on formation of the crystal. By contrast, in materials with gyrotropic order(3-6), electrons spontaneously organize themselves to exhibit macroscopic chirality in an originally achiral lattice. Although such order-which has been proposed as the quantum analogue of cholesteric liquid crystals-has attracted considerable interest(3-15), no clear observation or manipulation of gyrotropic order has been achieved so far. Here we report the realization of optical chiral induction and the observation of a gyrotropically ordered phase in the transition-metal dichalcogenide semimetal 1T-TiSe2. We show that shining mid-infrared circularly polarized light on 1T-TiSe2 while cooling it below the critical temperature leads to the preferential formation of one chiral domain. The chirality of this state is confirmed by the measurement of an out-of-plane circular photogalvanic current, the direction of which depends on the optical induction. Although the role of domain walls requires further investigation with local probes, the methodology demonstrated here can be applied to realize and control chiral electronic phases in other quantum materials(4,16).


Optical chiral induction and spontaneous gyrotropic electronic order are realized in the transition-metal chalcogenide 1T-TiSe2 by using illumination with mid-infrared circularly polarized light and simultaneous cooling below the critical temperature.


  
Warming of subarctic tundra increases emissions of all three important greenhouse gases - carbon dioxide, methane, and nitrous oxide 期刊论文
GLOBAL CHANGE BIOLOGY, 2017, 23 (8)
作者:  Voigt, Carolina;  Lamprecht, Richard E. .;  Marushchak, Maija E.;  Lind, Saara E.;  Novakovskiy, Alexander;  Aurela, Mika;  Martikainen, Pertti J.;  Biasi, Christina
收藏  |  浏览/下载:6/0  |  提交时间:2019/04/09
Arctic  climate change  DOC leaching  nitrogen cycle  OTC  peat plateau  permafrost  temperature manipulation  
Sensitivity of soil carbon fractions and their specific stabilization mechanisms to extreme soil warming in a subarctic grassland 期刊论文
GLOBAL CHANGE BIOLOGY, 2017, 23 (3)
作者:  Poeplau, Christopher;  Katterer, Thomas;  Leblans, Niki I. W.;  Sigurdsson, Bjarni D.
收藏  |  浏览/下载:4/0  |  提交时间:2019/04/09
global change  soil carbon fractionation  soil organic matter  soil warming  temperature manipulation  temperature sensitivity  trophic fractionation  delta C-13