ترغب بنشر مسار تعليمي؟ اضغط هنا

Diluted magnetism in Mn doped SrZnO2 single crystals

133   0   0.0 ( 0 )
 نشر من قبل Bommisetti Koteswararao Dr
 تاريخ النشر 2014
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

We have investigated the magnetic properties of Mn and Cu substituted SrZnO2 single crystals (SrZn0.99Mn0.01O2 and SrZn0.99Cu0.01O2). We observed signatures of weak ferromagnetism as a sharp increase of magnetic susceptibility below 5 K even in the low percentage (x= 0.01) of Mn substituted single crystals. Magnetic susceptibility data measured parallel or perpendicular to the ab plane yield anisotropic behavior with Curie Weiss temperature of about -320 K and -410 K, respectively, suggesting the presence of strong antiferromagnetic couplings among Mn atoms at high temperatures, similar to the Mn doped ZnO and Fe doped BaTiO3 samples. In contrast, the SrZn0.99Cu0.01O2 crystal shows paramagnetic behavior down to 2 K.



قيم البحث

اقرأ أيضاً

Using the first-principles density-functional theory plan-wave pseudopotential method, we investigate the structure and magnetism in 25% Mn substitutive and interstitial doped monoclinic, tetragonal and cubic ZrO2 systematically. Our studies show tha t the introduction of Mn impurities into ZrO2 not only stabilizes the high temperature phase, but also endows ZrO2 with magnetism. Based on the simple crystal field theory (CFT), we discuss the origination of magnetism in Mn doped ZrO2. Moreover, we discuss the effect of electron donor on magnetic semiconductors, and the possibility as electronic structure modulator.
The magnetism in 12.5% and 25% Mn delta-doped cubic GaN has been investigated using the density-functional theory calculations. The results show that the single-layer delta-doping and half-delta-doping structures show robust ground state half-metalli c ferromagnetism (HMF), and the double-layer delta-doping structure shows robust ground state antiferromagnetism (AFM) with large spin-flip energy of 479.0 meV per Mn-Mn pair. The delta-doping structures show enhanced two-dimensional magnetism. We discuss the origin of the HMF using a simple crystal field model. Finally, we discuss the antiferromagnet/ferromagnet heterostructure based on Mn doped GaN.
We have studied the electronic structure of Zn$_{0.9}$Fe$_{0.1}$O nano-particles, which have been reported to show ferromagnetism at room temperature, by x-ray photoemission spectroscopy (XPS), resonant photoemission spectroscopy (RPES), x-ray absorp tion spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD). From the experimental and cluster-model calculation results, we find that Fe atoms are predominantly in the Fe$^{3+}$ ionic state with mixture of a small amount of Fe$^{2+}$ and that Fe$^{3+}$ ions are dominant in the surface region of the nano-particles. It is shown that the room temperature ferromagnetism in the Zn$_{0.9}$Fe$_{0.1}$O nano-particles is primarily originated from the antiferromagnetic coupling between unequal amounts of Fe$^{3+}$ ions occupying two sets of nonequivalent positions in the region of the XMCD probing depth of $sim$ 2-3 nm.
166 - Z. Q. Liu , W. M. Lu , S. L. Lim 2012
The search for oxide-based room-temperature ferromagnetism has been one of the holy grails in condensed matter physics. Room-temperature ferromagnetism observed in Nb-doped SrTiO3 single crystals is reported in this Rapid Communication. The ferromagn etism can be eliminated by air annealing (making the samples predominantly diamagnetic) and can be recovered by subsequent vacuum annealing. The temperature dependence of magnetic moment resembles the temperature dependence of carrier density, indicating that the magnetism is closely related to the free carriers. Our results suggest that the ferromagnetism is induced by oxygen vacancies. In addition, hysteretic magnetoresistance was observed for magnetic field parallel to current, indicating that the magnetic moments are in the plane of the samples. The x-ray photoemission spectroscopy, the static time-of-flight and the dynamic secondary ion mass spectroscopy and proton induced x-ray emission measurements were performed to examine magnetic impurities, showing that the observed ferromagnetism is unlikely due to any magnetic contaminant.
383 - K. R. Simov 2017
Mn doping of group-IV semiconductors (Si/Ge) is achieved by embedding a thin Mn-film as a {delta}-doped layer in group-IV matrix. The Mn-layer consists of a dense layer of monoatomic Mn-wires, which are oriented perpendicular to the Si(001)-(2x1) dim er rows, or Mn-clusters. The nanostructures are covered with an amorphous Si or Ge capping layer, which conserves the identity of the {delta}-doped layer. The analysis of the bonding environment with STM is combined with the element-specific detection of the magnetic signature with X-ray magnetic circular dichroism. The largest moment (2.5 {mu}B/Mn) is measured for Mn-wires, which have ionic bonding character, with an a-Ge overlayer cap, a-Si capping leads to a slightly reduced moment which has its origin in subtle variation of bonding geometry. Our results directly confirm theoretical predictions on magnetism for Mn-adatoms on Si(001). The moment is quenched to 0.5{mu}B/Mn for {delta}-doped layers, which are dominated by clusters, and thus develop an antiferromagnetic component from Mn-Mn bonding.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا