اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدSpin-lattice and electron-phonon coupling in 3$d$/5$d$ hybrid Sr$_3$NiIrO$_6$
71
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
While 3$d$-containing materials display strong electron correlations, narrow band widths, and robust magnetism, 5$d$ systems are recognized for strong spin-orbit coupling, increased hybridization, and more diffuse orbitals. Combining these properties leads to novel behavior. Sr$_3$NiIrO$_6$, for example, displays complex magnetism and ultra-high coercive fields - up to an incredible 55~T. Here, we combine infrared and optical spectroscopies with high-field magnetization and first principles calculations to explore the fundamental excitations of the lattice and related coupling processes including spin-lattice and electron-phonon mechanisms. Magneto-infrared spectroscopy reveals spin-lattice coupling of three phonons that modulate the Ir environment to reduce the energy required to modify the spin arrangement. While these modes primarily affect exchange within the chains, analysis also uncovers important inter-chain motion. This provides a mechanism by which inter-chain interactions can occur in the developing model for ultra-high coercivity. At the same time, analysis of the on-site Ir$^{4+}$ excitations reveals vibronic coupling and extremely large crystal field parameters that lead to a t$_{2g}$-derived low-spin state for Ir. These findings highlight the spin-charge-lattice entanglement in Sr$_3$NiIrO$_6$ and suggest that similar interactions may take place in other 3$d$/5$d$ hybrids.
قيم البحث
اقرأ أيضاً
We have measured extremely large coercive magnetic fields of up to 55~T in Sr$_3$NiIrO$_6$, with a switched magnetic moment $approx 0.8~mu_{rm B}$ per formula unit. As far as we are aware, this is the largest coercive field observed thus far. This ex
traordinarily hard magnetism has a completely different origin from that found in conventional ferromagnets. Instead, it is due to the evolution of a frustrated antiferromagnetic state in the presence of strong magnetocrystalline anisotropy due to the overlap of spatially-extended Ir$^{4+}$ 5$d$ orbitals with oxygen 2$p$ and Ni$^{2+}$ 3$d$ orbitals. This work highlights the unusual physics that can result from combining the extended $5d$ orbitals in Ir$^{4+}$ with the frustrated behaviour of triangular lattice antiferromagnets.
We have studied the field and temperature dependence of the magnetization of single crystals of Sr3NiIrO6. These measurements evidence the presence of an easy axis of anisotropy and two anomalies in the magnetic susceptibility. Neutron powder diffrac
tion realized on a polycrystalline sample reveals the emergence of magnetic reflections below 75 K with magnetic propagation vector k ~ (0, 0, 1), undetected in previous neutron studies [T.N. Nguyen and H.-C zur Loye, J. Solid State Chem., 117, 300 (1995)]. The nature of the magnetic ground state, and the presence of two anomalies common to this family of material, are discussed on the basis of the results obtained by neutron diffraction, magnetization measurements, and symmetry arguments.
Sr$_{3}$ZnIrO$_{6}$ is an effective spin one-half Mott insulating iridate belonging to a family of magnets which includes a number of quasi-one dimensional systems as well as materials exhibiting three dimensional order. Here we present the results o
f an extensive investigation into the magnetism including heat capacity, a.c. susceptibility, muon spin rotation ($mu$SR), neutron diffraction and inelastic neutron scattering on the same sample. It is established that the material exhibits a transition at about $17$ K into a three-dimensional antiferromagnetic structure with propagation vector $boldsymbol{k}=(0,frac{1}{2},1)$ in the hexagonal setting of R$bar{3}$c and non-collinear moments of $0.87$$mu_B$ on Ir$^{4+}$ ions. Further we have observed a well defined powder averaged spin wave spectrum with zone boundary energy of $sim 5$ meV at $5$ K. We stress that a theoretical analysis shows that the observed non-collinear magnetic structure arises from anisotropic inter- and intra- chain exchange which has its origin in significant spin-orbit coupling. The model can satisfactorily explain the observed spin wave excitations.
Entanglement of spin and orbital degrees of freedom drives the formation of novel quantum and topological physical states. Discovering new spin-orbit entangled ground states and emergent phases of matter requires both experimentally probing the relev
ant energy scales and applying suitable theoretical models. Here we report resonant inelastic x-ray scattering measurements of the transition metal oxides Ca$_3$LiOsO$_6$ and Ba$_2$YOsO$_6$. We invoke an intermediate coupling approach that incorporates both spin-orbit coupling and electron-electron interactions on an even footing and reveal the ground state of $5d^3$ based compounds, which has remained elusive in previously applied models, is a novel spin-orbit entangled J=3/2 electronic ground state. This work reveals the hidden diversity of spin-orbit controlled ground states in 5d systems and introduces a new arena in the search for spin-orbit controlled phases of matter.
Polycrystalline sample of superconducting ThIr$_{3}$ was obtained by arc-melting Th and Ir metals. Powder x-ray diffraction revealed that the compound crystalizes in a rhombohedral crystal structure (R-3m, s.g. no. 166) with the lattice parameters: a
= 5.3394(1) $r{A}$ and c = 26.4228(8) $r{A}$. Normal and superconducting states were studied by magnetic susceptibility, electrical resistivity and heat capacity measurements. The results showed that ThIr$_{3}$ is a type II superconductor (Ginzburg-Landau parameter $kappa$ = 38) with the critical temperature T$_{c}$ = 4.41 K. The heat capacity data yielded the Sommerfeld coefficient $gamma$ = 17.6 mJ mol$^{-1}$ K$^{-2}$ and the Debye temperature $Theta_{D}$ = 169 K. The ratio $Delta$C / ($gamma$ T$_{c}$) = 1.6, where $Delta$C stands for the specific heat jump at T$_{c}$, and the electron-phonon coupling constant $lambda_{e-p}$ = 0.74 suggest that ThIr$_{3}$ is a moderate-strength superconductor. The experimental studies were supplemented by band structure calculations, which indicated that the superconductivity in ThIr$_{3}$ is governed mainly by 5d states of iridium. The significantly smaller band-structure value of Sommerfeld coefficient as well as the experimentally observed quadratic temperature dependence of resistivity and enhanced magnetic susceptibility suggest presence of electronic interactions in the system, which compete with superconductivity.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
