| 1. |
- Kamber, Umut, et al.
(författare)
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Self-induced spin glass state in elemental and crystalline neodymium
- 2020
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 368:6494
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Tidskriftsartikel (refereegranskat)abstract
- Spin glasses are a highly complex magnetic state of matter intricately linked to spin frustration and structural disorder. They exhibit no long-range order and exude aging phenomena, distinguishing them from quantum spin liquids. We report a previously unknown type of spin glass state, the spin-Q glass, observable in bulk-like crystalline metallic neodymium thick films. Using spin-polarized scanning tunneling microscopy combined with ab initio calculations and atomistic spin-dynamics simulations, we visualized the variations in atomic-scale noncolinear order and its response to magnetic field and temperature. We quantified the aging phenomena relating the glassiness to crystalline symmetry and the energy landscape. This result not only resolves the long-standing debate of the magnetism of neodymium, but also suggests that glassiness may arise in other magnetic solids lacking extrinsic disorder.
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| 2. |
- Verlhac, Benjamin, et al.
(författare)
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Thermally induced magnetic order from glassiness in elemental neodymium
- 2022
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Ingår i: Nature Physics. - : Nature Portfolio. - 1745-2473 .- 1745-2481. ; 18:8, s. 905-911
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Tidskriftsartikel (refereegranskat)abstract
- At finite temperatures, fluctuations invariably introduce disorder and are responsible for ultimately destroying ordered phases. Here we present an unusual magnetic transition in elemental neodymium where, with increasing temperature, long-range multiply periodic 'multi-Q' magnetic order emerges from a self-induced spin glass. Using temperature-dependent spin-polarized scanning tunnelling microscopy, we characterize the local order of a previously reported spin glass phase, and quantify the emergence of long-range multi-Q order with increasing temperature. We develop two analysis tools that allow us to determine the glass transition temperature from measurements of the spatially dependent magnetization. We compare these observations with atomistic spin dynamics simulations, which reproduce the qualitative observation of a phase transition from a low-temperature spin glass phase to an intermediate ordered multi-Q phase. These simulations trace the origin of the unexpected high-temperature order in weakened frustration driven by temperature-dependent sublattice correlations. These findings constitute an example of order from disorder, and provide a platform to study the rich magnetization dynamics of a self-induced spin glass.Thermal fluctuations associated with higher temperatures normally destroy long-range order, but in some circumstances they can stabilize new ordered phases. This 'order by disorder' phenomenon has now been observed in the magnetic phases of neodymium.
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| 3. |
- Wegner, Diana, et al.
(författare)
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Digital Human Modeling Requirements and Standardization.
- 2007
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Ingår i: 2007 Digital Human Modeling for Design and Engineering Conference and Exhibition, June 12-14, Seattle, Washington, USA..
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Konferensbidrag (refereegranskat)abstract
- This paper will initiate a discussion on automotiveindustry requirements and associated standardization ofdigital human modeling software (DHMS) as applied tomanufacturing operations. Industry benefits ofstandardization are vast, making it difficult to identify and provide an exhaustive list. High value benefits will belisted for the purpose of this discussion. Industry usersof DHMS will benefit by the standardization of anapplication programming interface, classification ofanthropometry and simulation data translation. A list ofhigh value standardization goals will be provided for thepurpose of this discussion. Two examples ofstandardization goals include 1) a reduction in the timeand cost required to integrate research results intocommercial software and 2) improved simulation datatransfer and linkages between DHMS to simplify the useof multiple tools when analyzing a single problem. Thispaper will provide an introduction to and proposal forstandardization of DHMS. It will introduce the concept ofa digital human modeling (DHM) architecture. It will alsoinclude a proposal on areas of standardization for futurediscussion.
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