The temperature dependence of the electron-spin resonance linewidth in La0.95Sr0.05MnO3 has been determined and analyzed in the paramagnetic regime across the orbital ordering transition. From the temperature dependence and the anisotropy of linewidth and g-value the orbital order can be unambiguously determined via the mixing angle of the wave functions of the eg-doublet. The linewidth shows a similar evolution with temperature as resonant x-ray scattering results.PACS numbers: 77.22. Gm, 64.70.Pf In transition-metal oxides the orbital degrees of freedom play an important role for the electric and magnetic properties. Their coupling to spin, charge and lattice is responsible for the occurrence of a variety of complex electronic ground states. Orbital order (OO) can be derived via the Jahn-Teller (JT) effect or via superexchange (SE) between degenerate orbitals under the control of strong Hund's-rule coupling [1]. Strong correlations exist between spin and orbital order and between OO and lattice distortions, but of course a one-to-one correspondence cannot be expected. While spin and lattice order can easily be detected experimentally, this is not true for OO and so far the OO parameter remains hidden. In recent years resonant x-ray scattering (RXS) has been used to derive information on the OO parameter [2], but there is an ongoing dispute, whether RXS probes the JT distortion or the orbital charge distribution [3,4]. Indirectly, OO can also be derived from diffraction experiments via lattice distortions and bond lengths [5]. In this Letter we demonstrate that electron-spin resonance (ESR) can be used to detect OO and to monitor the evolution of the OO parameter. Probing the spin of the partially filled d-shell of Mn 3+ ions by ESR, the anisotropy and T -dependence of g-value and linewidth ∆H provide clear information on OO via spin-orbit (SO) coupling.The power of ESR to gain insight into OO will be demonstrated on A-type antiferromagnetic (AFM) LaMnO 3 (T N =140 K), the parent compound of the magneto-resistance manganites and a paradigm for a cooperative JT effect that suggests a d 3x 2 −r 2 /d 3y 2 −r 2 -type OO below T N =750 K [6]. However, it has been shown that SE interactions play an important role, too [7]. Several recent studies exhibit clear anomalies of the ESR parameters at the JT transition in both doped and pure LaMnO 3 [8,9,10,11]. The orbitally ordered O ′ -phase is characterized by an anisotropy of ∆H [11,12], which for polycrystalline samples reduces to a broad maximum in ∆H(T ) [9,10]. Previously, the angular dependencies of ∆H and the resonance field H res had been analyzed for 200 K and 300 K in high-temperature approximation, allowing to estimate the Dzyaloshinsky-Moriya (DM) interaction and the strength of the zero-field splitting (ZFS) parameters [13]. At X-Band frequencies (9 GHz) ∆H was of the same order of magnitude as H res and due to the overlap with the resonance at −H res and their mutual coupling via the nondiagonal elements of the dynamic susceptibility [14] the values for ...
We present a model calculation of the paramagnetic-resonance linewidth in La 0.95 Sr 0.05 MnO 3. Both the temperature and the angular dependencies can be described by contributions from the crystal field due to the cooperative Jahn–Teller transition.
На модели терминальной анестезии роговицы глаза кролика установлено, что третичные производные диметилацетамида с L-глутаминовой (ЛХТ-3-00) кислотой в концентрации 2 % и N-ацетил-L-глутаминовой (ЛХТ-4-00) кислотой в диапазоне концентраций от 0,5 до 2 % превосходят структурный предшественник лидокаин в аналогичных концентрациях по глубине на 57,2 и 104,1 % (p = 0,018) и длительности на 9,6 и 27,2 % (p = 0,003) местноанестезирующего действия, соответственно, но уступают тетракаину. Соединения менее токсичны, чем лидокаин в среднем на 27 % и тетракаин в среднем в 7,5 раз при подкожном введении мышам, не вызывают местного раздражающего эффекта и обладают большей широтой терапевтического действия.
В работе изучено противоопухолевое действие соединения 4H-аминохромена на ксенографтной модели ALK-экспрессирующей аденокарциномы легкого у гуманизированных nude BALB/c мышей. Установлено, что внутрижелудочное введение соединения вызывает дозозависимое сокращение опухолевого узла, снижение частоты метастазирования, повышает выживаемость животных – носителей ксенографта. В основе эффекта соединения лежит подавление экспрессии рецепторной тирозинкиназы и тубулина-бета 3 в ткани опухоли, а также активация каспаза-3-зависимой программируемой гибели опухолевых клеток. Полученные результаты позволяют рассматривать соединение 4H-аминохромена АХ-554 как перспективное для разработки на его основе молекулярно-направленного лекарственного средства.
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