اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدSuppression of long-range ordering and multiferroicity in Sr-substituted Ba3-xSrxMnNb2O9 (x = 1 and 3)
104
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Effects of Sr substitution at A-site in ordered perovskite Ba3-xSrxMnNb2O9 (x = 1 and 3) have been investigated using X-ray diffraction, magnetization, dielectric/magnetodielectric and neutron diffraction measurements. The parent compound Ba3MnNb2O9 having a large spin (S=5/2) is known to exhibit type-II multiferroic properties with quasi 2D triangular lattice antiferromagnetic ground state. A slight perturbation in exchange interaction due to substitution of smaller size isovalent ion at the A-site in Ba3-xSrxMnNb2O9 (x = 1 and 3) has been found to alter the ground states drastically and hence the multiferroicity. The crucial role of various fluctuations (quantum and/or thermal), weak lattice distortion induced by Sr-substitution and slight imbalance between different fluctuations in determining the ground states and the multiferroicity is discussed and compared with the results of smaller spin compounds (S = 1/2 or 1).
قيم البحث
اقرأ أيضاً
The double-perovskite A$_2$BBO$_6$ with heavy transition metal ions on the ordered B sites is an important family of compounds to study the interplay between electron correlation and spin-orbit coupling (SOC). Here we prepared high-quality Sr$_2$MgRe
O$_6$ powder and single-crystal samples and performed non-resonant and resonant synchrotron x-ray diffraction experiments to investigate its magnetic ground state. By combining the magnetic susceptibility and heat capacity measurements, we conclude that Sr$_2$MgReO$_6$ exhibits a layered antiferromagnetic (AF) order at temperatures below $sim$ 55 K with a propagation vector q = (001), which contrasts the previously suspected spin glass state. Our works clarify the magnetic order in Sr$_2$MgReO$_6$ and demonstrate it as a candidate system to look for magnetic octupolar orders and exotic spin dynamics.
A laboratory hard X-ray photoelectron spectroscopy (HXPS) system equipped with a monochromatic Cr K$alpha$ ($h u = 5414.7$ eV) X-ray source was applied to an investigation of the core-level electronic structure of La$_{1-x}$Sr$_x$MnO$_3$. No apprecia
ble high binding-energy shoulder in the O $1s$ HXPS spectra were observed while an enhanced low binding-energy shoulder structure in the Mn $2p_{3/2}$ HXPS spectra were observed, both of which are manifestation of high bulk sensitivity. Such high bulk sensitivity enabled us to track the Mn $2p_{3/2}$ shoulder structure in the full range of $x$, giving us a new insight into the binding-energy shift of the Mn $2p_{3/2}$ core level. Comparisons with the results using the conventional laboratory XPS ($h u = 1486.6$ eV) as well as those using a synchrotron radiation source ($h u = 7939.9$ eV) demonstrate that HXPS is a powerful and convenient tool to analyze the bulk electronic structure of a host of different compounds.
A detailed electronic phase diagram of perovskite-type oxides Sr$_{1-x}$La$_x$FeO$_3$ $(0leq x leq 0.5)$ was established by synchrotron X-ray diffraction, magnetization, and transport measurements for polycrystalline samples synthesized by a high-pre
ssure technique. Among three kinds of helimagnetic phases in SrFeO$_3$ at zero field, two of them showing multiple-${it q}$ helimagnetic spin textures tend to rapidly disappear in cubic symmetry upon the La substitution with $x$ less than 0.1, which accompanies the loss of metallic nature. On the other hand, the third helimagnetic phase apparently remains robustly in Sr$_{1-x}$La$_x$FeO$_3$ with $x$ higher than 0.1, followed by merging to the spin/charge ordered phase with $xsim 1/3$. We propose an important role of itinerant ligand holes on the emergence of multiple-${it q}$ states and a possible link between the third (putative single-${it q}$) helimagnetic phase in SrFeO$_3$ and the spin/charge ordered phase in Sr$_{2/3}$La$_{1/3}$FeO$_3$.
The orthorhombic Haldane spin chain compound Tb2BaNiO5 (Neel order, TN1= 63 K) has been shown to be an exotic multiferroic system below (TN2) 25 K due to various fascinating features, pointing to a strong potential for the advancement of concepts in
this field. In particular, the rare-earth ions play a direct decisive role unlike in many other well known multiferroic materials and there appears to be a critical canting angle, developing below TN2, subtended by Tb 4f and Ni 3d moments to trigger this cross coupling phenomenon. However, for a small replacement of Sr for Ba, viz. in Tb2Ba0.9Sr0.1NiO5, ferroelectricity was reported to get destroyed, but retaining magnetic features at (TN1) 55 K and (TN2) 14 K. In this article, we address the origin of suppression of multiferrocity in this Sr doped system through neutron diffraction studies and density functional theory calculations. We find that, unlike in Tb2BaNiO5, there is no pronounced change in the relative canting angle of the magnetic moments around TN2 and that the absolute value of this parameter down to 2 K fails to exceed the critical value noted for the parent, thereby explaining the origin of destruction of magnetoelectric coupling in the Sr doped material. This finding renders strong support to the proposal of possible existence of critical canting angle, at least in some cases, to induce multiferroicity, apart from serving as a route to engineer multiferroic materials for applications.
We study magnetic and multiferroic behavior in Ca$_3$Co$_{2-x}$Mn$_{x}$O$_6$ ($x sim$0.97) by high-field measurements of magnetization ($M$), magnetostriction ($L$($H$)/$L$), electric polarization ($P$), and magnetocaloric effect. This study also giv
es insight into the zero and low magnetic field magnetic structure and magnetoelectric coupling mechanisms. We measured $M$ and $Delta$$L$/$L$ up to pulsed magnetic fields of 92 T, and determined the saturation moment and field. On the controversial topic of the spin states of Co$^{2+}$ and Mn$^{4+}$ ions, we find evidence for $S$ = 3/2 spins for both ions with no magnetic field-induced spin-state crossovers. Our data also indicate that Mn$^{4+}$ spins are quasi-isotropic and develop components in the $ab$-plane in applied magnetic fields of 10 T. These spins cant until saturation at 85 T whereas the Ising Co$^{2+}$ spins saturate by 25 T. Furthermore, our results imply that mechanism for suppression of electric polarization with magnetic fields near 10 T is flopping of the Mn$^{4+}$ spins into the $ab$-plane, indicating that appropriate models must include the coexistence of Ising and quasi-isotropic spins.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
