| 1. |
|
|
| 2. |
|
|
| 3. |
- Garmroudi, F., et al.
(author)
-
Unveiling the structure-property relationship in metastable Heusler compounds by systematic disorder tuning
- 2023
-
In: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 107:1
-
Journal article (peer-reviewed)abstract
- Heusler compounds represent a unique class of materials that exhibit a wide range of fascinating and tuneable properties such as exotic magnetic phases, superconductivity, band topology, or thermoelectricity. An exceptional, but for Heusler compounds common, feature is that they are prone to antisite defects and disorder. In this regard, the Fe2VAl Heusler compound has been a particularly interesting and disputed candidate. Even though various theoretical scenarios for the interplay of physical properties and disorder have been proposed, the metastable disordered A2 phase hitherto precluded experimental investigation in bulk samples. Here, we report experimental results on disorder-tuned Fe2VAl0.9Si0.1 alloys all the way toward the A2 phase, which we realized via rapidly quenching our samples from high temperatures. We measured the thermoelectric properties of these materials in a wide temperature range (4 to 700 K); they suggest a gradual semimetal/narrow-gap semiconductor -> metal transition upon increasing the disorder. We also find a large anomalous Hall effect in the disordered A2 phase, arising from the side-jump scattering of charge carriers at the antisite magnetic moments. This is corroborated by measurements of the temperature-and field-dependent magnetization, which increases dramatically up to approximate to 2.5 mu B/f.u. as compared to the ordered compound (<0.1 mu B/f.u.). This study provides an experimental realization of the metastable A2 structure in bulk Fe2VAl-based alloys and grants insight into the structure-property relationship of these materials. Our work confirms that temperature-induced antisite disorder, occurring during thermal heat treatment, can be a precisely tuneable parameter in the family of Heusler compounds.
|
|
| 4. |
- Renk, O., et al.
(author)
-
Stainless steel reveals an anomaly in thermal expansion behavior of severely deformed materials
- 2021
-
In: Physical Review Materials. - : American Physical Society (APS). - 2475-9953. ; 5:11
-
Journal article (peer-reviewed)abstract
- Thermal expansion of materials is of fundamental practical relevance and arises from an interplay of several material properties. For nanocrystalline materials, accurate measurements of thermal expansion based on highprecision reference dilatometry allow inferring phenomena taking place at internal interfaces such as vacancy annihilation at grain boundaries. Here we report on measurements obtained for a severely deformed 316L austenitic steel, showing an anomaly in difference dilatometry curves which we attribute to the exceptionally high density of stacking faults. On the basis of ab intio simulations we report evidence that the peculiar magnetic state of the 316L austenitic steel causes stacking faults to expand more than the matrix. So far, the effect has only been observed for this particular austenitic steel but we expect that other magnetic materials could exhibit an even more pronounced anomaly.
|
|
