تقرير
Correlations between stacked structures and weak itinerant magnetic properties of La$_{2-x}$ Y$_x $ Ni$_7$ compounds
| العنوان: | Correlations between stacked structures and weak itinerant magnetic properties of La$_{2-x}$ Y$_x $ Ni$_7$ compounds |
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| المؤلفون: | Paul-Boncour, Valérie, Crivello, Jean-Claude, Madern, Nicolas, Zhang, Junxian, Diop, Léopold, Charbonnier, Véronique, Monnier, Judith, Latroche, Michel |
| المصدر: | Journal of Physics: Condensed Matter, Vol. 32, 2020, Numb. 41, p. 415804 |
| سنة النشر: | 2019 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Materials Science |
| الوصف: | Hexagonal La$_2$Ni$_7$ and rhombohedral Y$_2$Ni$_7$ are weak itinerant antiferromagnet (wAFM) and ferromagnet (wFM), respectively. The crystal structure and magnetic properties of $A_2B_7$ intermetallic compounds ($A$ = La, Y, $B$ = Ni) have been investigated combining X-ray powder diffraction and magnetic measurements. The La$_{2-x}$Y$_x$Ni$_7$ intermetallic compounds with $0 \leq x \leq 1$ crystallize in the Ce$_{2}$Ni$_7$-type hexagonal structure with Y preferentially located in the [$AB_2$] units. The compounds with larger Y content ($1.2 \leq x < 2$) crystallize in both hexagonal and rhombohedral (Gd$_2$Co$_7$-type) structures with a progressive substitution of Y for La in the $A$ sites belonging to the [$AB_5$] units. Y$_2$Ni$_7$ crystallizes in the rhombohedral structure only. The average cell volume decreases linearly versus Y content, whereas the c/a ratio presents a minimum at $x = 1$ due to geometric constrains. The magnetic properties are strongly dependent on the structure type and the Y content. La$_{2}$Ni$_7$ displays a complex metamagnetic behavior with split AFM peaks. Compounds with x = 0.25 and 0.5 display a wAFM ground state and two metamagnetic transitions, the first one towards an intermediate wAFM state and the second one towards a FM state.T$_N$ and the second critical field increase with the Y content, indicating a stabilization of the AFM state. LaYNi$_7$, which is as the boundary between the two structure types, presents a very wFM state at low field and an AFM state as the applied field increases. All the compounds with $x > 1$ and containing a rhombohedral phase are wFM with $T_C$ = 53(2) K. In addition to the experimental studies, first principles calculations using spin polarization have been performed to interpret the evolution of both structural phase stability and magnetic ordering for $0 \leq x < 2$. Comment: 26 pages (7 for supplementary material), 4 tables, 9 main figures and 8 figures in supplementary material |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1088/1361-648X/ab9d4c |
| URL الوصول: | http://arxiv.org/abs/1905.01985 |
| رقم الأكسشن: | edsarx.1905.01985 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1088/1361-648X/ab9d4c |
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