اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديد19-F NMR Investigation of Iron-pnictide Superconductor LaFeAsO(0.89)F(0.11)
134
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We report 19-F NMR investigation of the new high temperature superconductor LaFeAsO(0.89)F(0.11) (Tc ~ 28K). We demonstrate that low frequency spin fluctuations exhibit pseudo gap behavior above Tc. We also deduce the London penetration depth lambda from NMR line broadening below Tc.
قيم البحث
اقرأ أيضاً
We report on an experimental study of the effect of Mn impurities in the optimally doped LaFeAsO$_{0.89}$F$_{0.11}$ compound. The results show that a very tiny amount of Mn, of the order of 0.1%, is enough to destroy superconductivity and to recover
at low temperatures both the magnetic ground state and the orthorhombic structure of the pristine LaFeAsO parent compound. The results are discussed within a model where electron correlations enhance the Ruderman-Kittel-Kasuya-Yosida interaction among impurities.
The electronic structure in the normal state of CeFeAsO0.89F0.11 oxypnictide superconductors has been investigated with x-ray absorption and photoemission spectroscopy. All the data exhibit signatures of Fe d-electron itinerancy. Exchange multiplets
appearing in the Fe 3s core level indicate the presence of itinerant spin fluctuations. These findings suggest that the underlying physics and the origin of superconductivity in these materials are likely to be quite different from those of the cuprate high-temperature superconductors. These materials provide opportunities for elucidating the role of magnetic fluctuations in high-temperature superconductivity.
We will probe the intrinsic behavior of spin susceptibility chi_(spin) in the LaFeAsO(1-x)F(x) superconductor (x ~ 0.1, Tc ~ 27K) using 19-F and 75-As NMR techniques. Our new results firmly establish the pseudo-gap behavior with Delta_(PG)/kB ~ 140K.
The estimated magnitude of chi_(spin) at 290K, ~1.8x10^(-4) [emu/mol-Fe], is approximately twice larger than that in high Tc cuprates. We also show that chi_(spin) levels off below ~50K down to Tc.
We present $^{75}$As Nuclear Magnetic and Quadrupole Resonance results (NMR, NQR) on a new set of LaFeAsO$_{1-x}$F$_x$ polycrystalline samples. Improved synthesis conditions led to more homogenized samples with better control of the fluorine content.
The structural$equiv$nematic, magnetic, and superconducting transition temperatures have been determined by NMR spin-lattice relaxation rate and AC susceptibility measurements. The so-determined phase diagram deviates from the published one especially for low F-doping concentrations. However, if the doping level is determined from the NQR spectra, both phase diagrams can be reconciled. The absence of bulk coexistence of magnetism and superconductivity and a nanoscale separation into low-doping-like and high-doping-like regions have been confirmed. Additional frequency dependent intensity, spin-spin, and spin-lattice relaxation rate measurements on underdoped samples at the boundary of magnetism and superconductivity indicate that orthorhombicity and magnetism originate from the low-doping-like regions, and superconductivity develops at first in the high-doping-like regions.
A new iron pnictide LiFeP superconductor was found. The compound crystallizes into a Cu2Sb structure containing an FeP layer showing superconductivity with maximum Tc of 6K. This is the first 111 type iron pnictide superconductor containing no arseni
c. The new superconductor is featured with itinerant behavior at normal state that could helpful to understand the novel superconducting mechanism of iron pnictide compounds.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
