Magnetic anisotropy in YbAlO3 studied by electron spin resonance

The magnetic anisotropy of the quantum-critical spin-chain system YbAlO$$_3$$is studied in detail in its paramagnetic phase by means of electron spin resonance. We find an uniaxial g factor anisotropy with $$g_\parallel =7.01$$and $$g_\perp = 0.47$$. The existence of two distinct magnetic Yb sites explains the resonance spectra well

Computational study of LnGaO3 (Ln=La+Gd) perovskites

Atomistic simulation techniques have been used to study the thermal properties of perovskite-type LnGaO3 (Ln = La-Gd). A set of interatomic potentials describing interatomic interactions in these compounds was developed and tested over a wide temperature range through utilizing free energyminimization.The predicted dielectric constants, thermal expansion coefficients, phonon density of states and its projections, heat capacity and entropy, elastic moduli, Gruneisen parameters, surface energies for main crystallographic directionsand Debye temperatures are in good agreement with the limited available experimental data. Perovskite-type LnGaO3 (Ln = La-Gd) compounds have been examined under conditions to which substrate materials are typically subjected. Only a narrow region in the phase diagram of LnGaO3 (Ln = La-Gd) and their solid solutions is recommended for use in substrate applications

Antiferromagnetic ordering and dipolar interactions of YbAlO3_3

In this paper we report low-temperature magnetic properties of the rare-earth perovskite material YbAlO$_3$. Results of elastic and inelastic neutron scattering experiment, magnetization measurements along with the crystalline electrical field (CEF) calculations suggest that the ground state of Yb moments is a strongly anisotropic Kramers doublet, and the moments are confined in the $ab$-plane, pointing at an angle of $\varphi = \pm 23.5^{\circ}$ to the $a$-axis. With temperature decreasing below $T_{\rm N}=0.88$ K, Yb moments order into the coplanar, but non-collinear antiferromagnetic (AFM) structure $AxGy$, where the moments are pointed along their easy-axes. In addition, we highlight the importance of the dipole-dipole interaction, which selects the type of magnetic ordering and may be crucial for understanding magnetic properties of other rare-earth orthorhombic perovskites. Further analysis of the broad diffuse neutron scattering shows that one-dimensional interaction along the $c$-axis is dominant, and suggests YbAlO$_3$ as a new member of one dimensional quantum magnets.Comment: 8 pages, 6 figure

Structural, magnetic, dielectric and mechanical properties of (Ba,Sr)MnO3_3 ceramics

Ceramic samples, produced by conventional sintering method in ambient air, 6H-SrMnO$_3$(6H-SMO), 15R-BaMnO$_3$(15R-BMO), 4H-Ba$_{0.5}$Sr$_{0.5}$MnO$_3$(4H-BSMO) were studied. In the XRD measurements for SMO the new anomalies of the lattice parameters at 600-800 K range and the increasing of thermal expansion coefficients with a clear maximum in a vicinity at 670 K were detected. The N$\acute{e}$el phase transition for BSMO was observed at $T_N$=250 K in magnetic measurements and its trace was detected in dielectric, FTIR, DSC, and DMA experiments. The enthalpy and entropy changes of the phase transition for BSMO at $T_N$ were determined as 17.5 J/mol and 70 mJ/K mol, respectively. The activation energy values and relaxation times characteristic for relaxation processes were determined from the Arrhenius law. Results of ab initio simulations showed that the contribution of the exchange correlation energy to the total energy is about 30%.Comment: 12 pages, 12 figure

Multiple fermion scattering in the weakly coupled spin-chain compound YbAlO3

The Heisenberg antiferromagnetic spin-1/2 chain, originally introduced almost a century ago, is one of the best studied models in quantum mechanics due to its exact solution, but nevertheless it continues to present new discoveries. Its low-energy physics is described by the Tomonaga-Luttinger liquid of spinless fermions, similar to the conduction electrons in one-dimensional metals. In this work we investigate the Heisenberg spin-chain compound YbAlO3 and show that the weak interchain coupling causes Umklapp scattering between the left- and right-moving fermions and stabilizes an incommensurate spin-density wave order at q = 2kF under finite magnetic fields. These Umklapp processes open a route to multiple coherent scattering of fermions, which results in the formation of satellites at integer multiples of the incommensurate fundamental wavevector Q = nq. Our work provides surprising and profound insight into bandstructure control for emergent fermions in quantum materials, and shows how neutron diffraction can be applied to investigate the phenomenon of coherent multiple scattering in metals through the proxy of quantum magnetic systems

Multiple fermion scattering in the weakly coupled spin-chain compound YbAlO3

The Heisenberg antiferromagnetic spin-1/2 chain, originally introduced almost a century ago, is one of the best studied models in quantum mechanics due to its exact solution, but nevertheless it continues to present new discoveries. Its low-energy physics is described by the Tomonaga-Luttinger liquid of spinless fermions, similar to the conduction electrons in one-dimensional metals. In this work we investigate the Heisenberg spin-chain compound YbAlO3 and show that the weak interchain coupling causes Umklapp scattering between the left- and right-moving fermions and stabilizes an incommensurate spin-density wave order at q = 2kF under finite magnetic fields. These Umklapp processes open a route to multiple coherent scattering of fermions, which results in the formation of satellites at integer multiples of the incommensurate fundamental wavevector Q = nq. Our work provides surprising and profound insight into bandstructure control for emergent fermions in quantum materials, and shows how neutron diffraction can be applied to investigate the phenomenon of coherent multiple scattering in metals through the proxy of quantum magnetic systems

Multiple fermion scattering in the weakly coupled spin-chain compound YbAlO3

The Heisenberg antiferromagnetic spin-1/2 chain, originally introduced almost a century ago, is one of the best studied models in quantum mechanics due to its exact solution, but nevertheless it continues to present new discoveries. Its low-energy physics is described by the Tomonaga-Luttinger liquid of spinless fermions, similar to the conduction electrons in one-dimensional metals. In this work we investigate the Heisenberg spin-chain compound YbAlO3 and show that the weak interchain coupling causes Umklapp scattering between the left- and right-moving fermions and stabilizes an incommensurate spin-density wave order at q = 2kF under finite magnetic fields. These Umklapp processes open a route to multiple coherent scattering of fermions, which results in the formation of satellites at integer multiples of the incommensurate fundamental wavevector Q = nq. Our work provides surprising and profound insight into bandstructure control for emergent fermions in quantum materials, and shows how neutron diffraction can be applied to investigate the phenomenon of coherent multiple scattering in metals through the proxy of quantum magnetic systems

DAMPAK WISATAWAN ASING TERHADAP PERUBAHAN SOSIAL BUDAYA MASYARAKAT (STUDI PADA MASYARAKAT DI KEC. LHOKNGA KAB. ACEH BESAR)

ABSTRAKBerkembangnya pariwisata di tengah masyarakat membawa pengaruh terhadap kehidupan sosial budaya. Pariwisata selalu mempertemukan dua atau lebih kebudayaan yang akan menghasilkan berbagai proses perubahan seperti akulturasi, dominasi, asimilasi, adopsi, adaptasi dan sebagainya. Wisatawan mancanegara yang berkunjung ke Lhoknga telah membawa pengaruh terhadap masyarakat lokal di daerah sekitar objek wisata. Penelitian ini bertujuan untuk mengetahui dampak pariwisata terhadap perubahan sosial budaya masyarakat dan mengetahui bentuk perubahan sosial budaya yang terjadi pada masyarakat Lhoknga akibat perkembangan pariwisata di Mukim Lhoknga. Metodologi penelitian ini menggunakan pendekatan kualitatif dengan model studi deskriptif. Pengumpulan data dilakukan dengan wawancara mendalam dan observasi. Dari hasil penelitian menunjukkan bahwa terjadinya perubahan sosial budaya pada masyarakat lokal di Mukim Lhoknga, Kecamatan Lhoknga Kabupaten Aceh Besar. Namun perubahan yang dimaksud masih dikategorikan perubahan secara mikro, karena tidak membawa pengaruh yang mendalam pada kehidupan masyarakat lokal. Dampak pariwisata terhadap perubahan sosial budaya masyarakat dapat dipilah menjadi dua yaitu dampak positif dan dampak negatif. Dampak positifnya yaitu dengan adanya pariwisata telah membuka lapangan kerja baru bagi masyarakat lokal yang dapat meningkatkan pendapatan ekonomi, mampu menguasai bahasa asing, seperti bahasa Inggris, Jepang. Terbukanya akses bagi masyarakat lokal ke jaringan yang lebih luas, memperlihatkan keindahan alam dan budaya yang tak lepas dari rasa untuk meningkatkan persaudaraan dalam lingkungan nasional dan internasional Sedangkan dampak negatif yaitu, lunturnya budaya lokal (tradisional) akibat masuknya budaya luar (modern). Adapun bentuk-bentuk perubahan dapat dilihat dari dua segi yaitu perubahan segi sosial dan perubahan dari segi budaya. Bentuk perubahan dari segi sosial yaitu terjadinya perubahan struktur sosial masyarakat lokal dengan beralihnya sektor pekerjaan dari petani atau nelayan ke sektor industri, Meningkatnya keinginan untuk berpendidikan tinggi, sedangkan perubahan dari segi budaya yaitu terjadinya perkawinan dari dua unsur budaya yang berbeda, perubahan pada penggunaan bahasa, perubahan cara berpakaian dan perubahan perilaku dalam keluarga.Kata Kunci : Pariwisata, Wisatawan Asing, Perubahan Sosial, Perubahan Budaya.Banda Ace

k=0Magnetic Structure and Absence of Ferroelectricity in SmFeO3

SmFeO3 has attracted considerable attention very recently due to the reported multiferroic properties above room-temperature. We have performed powder and single crystal neutron diffraction as well as complementary polarization dependent soft X-ray absorption spectroscopy measurements on floating-zone grown SmFeO3 single crystals in order to determine its magnetic structure. We found a k=0 G-type collinear antiferromagnetic structure that is not compatible with inverse Dzyaloshinskii-Moriya interaction driven ferroelectricity. While the structural data reveals a clear sign for magneto-elastic coupling at the N\'eel-temperature of ~675 K, the dielectric measurements remain silent as far as ferroelectricity is concerned

Tomonaga–Luttinger liquid behavior and spinon confinement in YbAlO 3

Low dimensional quantum magnets are interesting because of the emerging collective behavior arising from strong quantum fluctuations. The one-dimensional (1D) S = 1/2 Heisenberg antiferromagnet is a paradigmatic example, whose low-energy excitations, known as spinons, carry fractional spin S = 1/2. These fractional modes can be reconfined by the application of a staggered magnetic field. Even though considerable progress has been made in the theoretical understanding of such magnets, experimental realizations of this low-dimensional physics are relatively rare. This is particularly true for rare-earth-based magnets because of the large effective spin anisotropy induced by the combination of strong spin–orbit coupling and crystal field splitting. Here, we demonstrate that the rare-earth perovskite YbAlO3 provides a realization of a quantum spin S = 1/2 chain material exhibiting both quantum critical Tomonaga–Luttinger liquid behavior and spinon confinement–deconfinement transitions in different regions of magnetic field–temperature phase diagram