اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدOxygen vacancy induced re-entrant spin glass behavior in multiferroic ErMnO3 thin films
147
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
Epitaxial thin films of hexagonal ErMnO3 fabricated on Pt(111)/Al2O3(0001) and YSZ(111) substrates exhibited both ferroelectric character and magnetic ordering at low temperatures. As the temperature was reduced, the ErMnO3 films first showed antiferromagnetism. At lower temperatures, the films deposited at lower oxygen partial pressures exhibited spin glass behavior. This re-entrant spin glass behavior was attributed to competition between an antiferromagnetic interaction in the hexagonal geometry and a ferromagnetic interaction caused by a change in Mn valence induced by excess electrons from the oxygen vacancies.
قيم البحث
اقرأ أيضاً
The static critical phenomenology near the Curie temperature of the re-entrant metallic alloys Au_0.81Fe_0.19, Ni_0.78Mn_0.22, Ni_0.79Mn_0.21 and amorphous a-Fe_0.98Zr_0.08 is studied using a variety of experimental techniques and methods of analysis
. We have generally found that the values for the exponents alpha, beta, gamma and delta depart significantly from the predictions for the 3D Heisenberg model and are intermediate between these expectations and the values characterizing a typical spin glass transition. Comparing the exponents obtained in our work with indices for other re-entrant systems reported in the literature, a weak universality class may be defined where the exponents distribute within a certain range around average values.
We report the observation of spin-glass-like behavior and strong magnetic anisotropy in extremely smooth (~1-3 AA) roughness) epitaxial (110) and (010) SrRuO3 thin films. The easy axis of magnetization is always perpendicular to the plane of the film
(unidirectional) irrespective of crystallographic orientation. An attempt has been made to understand the nature and origin of spin-glass behavior, which fits well with Heisenberg model.
We report the results of neutron diffraction, ac and dc magnetization, heat-capacity, complex permittivity, and pyrocurrent measurements on an oxide, Li3NiRuO5, hitherto not paid much attention in the literature, except for a previous report on its p
romising electrochemical performance. We emphasize on the following findings: (i) Observation of re-entrant spin-glass behavior; that is, this oxide undergoes ferrilmagnetic ordering below 8- K, entering spin-glass regime around 12 K. (ii) There is no prominent feature in the complex dielectric permittivity (in particular, at the magnetic transitions) in the absence of external magnetic field, indicative of the absence of ferroelectricity. However, there is a distinct evidence for magneto-dielectric (MDE) coupling. The sign of MDE coupling also changes as the sample is cooled from ferrimagnetic state to spin-glass regime. (iii) There are pyroelectric anomalies in the vicinity of 30-70 K, presumably from thermally stimulated depolarization current.
We have synthesized highly oxygen deficient HfO$_{2-x}$ thin films by controlled oxygen engineering using reactive molecular beam epitaxy. Above a threshold value of oxygen vacancies, p-type conductivity sets in with up to 6 times 10^{21} charge carr
iers per cm3. At the same time, the band-gap is reduced continuously by more than 1 eV. We suggest an oxygen vacancy induced p-type defect band as origin of the observed behavior.
The ferromagnetic phase of an Ising model in d=3, with any amount of quenched antiferromagnetic bond randomness, is shown to undergo a transition to a spin-glass phase under sufficient quenched bond dilution. This general result, demonstrated here wi
th the numerically exact renormalization-group solution of a d=3 hierarchical lattice, is expected to hold true generally, for the cubic lattice and for quenched site dilution. Conversely, in the ferromagnetic-spinglass-antiferromagnetic phase diagram, the spin-glass phase expands under quenched dilution at the expense of the ferromagnetic and antiferromagnetic phases. In the ferro-spinglass phase transition induced by quenched dilution reentrance is seen, as previously found for the ferro-spinglass transition induced by increasing the antiferromagnetic bond concentration.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
