Stabilization of magnetic polarons in antiferromagnetic semiconductors by extended spin distortions

We study the problem of a magnetic polaron in an antiferromagnetic semiconductor (ferron). We obtain an analytical solution for the distortion produced in the magnetic structure of the d-spins due to the presence of a charge carrier bound to an impurity. The region in which the charge carrier is trapped is of the order of the lattice constant (small ferron) but the distortion of the magnetic structure extends over much larger distance. It is shown that the presence of this distortion makes the ferron more stable, and introduces a new length scale in the problem.Comment: 5 pages, 1 figure, RevTex 4, submitted to PRB; v2: one reference added, minor changes in the experiment discussion; v3: minor changes in tex

PEMBELAJARAN MEMBANDINGKAN TEKS CERITA PENDEK DENGAN TEKS EKSPLANASI KOMPLEKS MENGGUNAKAN MODEL COOPERATIVE INTEGRATED READING AND COMPOSITION PADA SISWA KELAS XI SMA NEGERI 18 BANDUNG TAHUN PELAJARAN 2016/2017

Dalam penulisan skripsi ini penulis mengajukan r um usan masalah (1) m am - pukah penulis melaks a nakan pembelajaran membandingkan teks cerita pendek dengan teks eksplanasi kompleks dengan menggunakan model cooperative integ - rated reading and com position pada siswa kelas X I SMA N 18 Ban dung? ; (2) m ampukah siswa kelas X I SMAN 18 Bandung melakukan pembelajaran mem - bandingkan teks cerita pendek dengan teks eksplanasi kompleks menggunakan m odel cooperative integrated reading and composition ? ; (3) e fektifkah mode l co - operative integrated reading and composition diterapkan dalam pembelajaran membandingkan teks cerita pendek dengan teks eks planasi kompleks pada siswa kelas X I SMA Negeri 18 Bandung ? Penenelitian ini bertu juan untuk mengetahui kemampuan penulis, kemampuan siswa dan ketepat an model cooperative integra - ted reading and composition dalam pem belajaran me mbandingkan teks cerita pendek dengan teks eksplanasi kompleks menggunakan m ode l cooperative integ - rated reading and composition pada siswa kelas X I SM AN 18 Ba ndung . Hipotesis yang penulis rumuskan yaitu: (1) p enulis mampu melaksanakan pembelajaran membandingkan teks cerita pendek dengan teks eksplanasi kom - pleks menggunakan model cooperative integrated reading and composition pada siswa kelas X I SMAN 18 Bandung ; (2) s iswa kelas X I SMA N 18 Bandung mam - pu mengikuti pembelajaran membandingkan teks cerita pendek dengan teks eks - planasi kompleks dalam bentuk tulisan berdasarkan struktur kedua teks ; (3) m odel cooperative integrated reading and composition efektif digunakan dalam pembe - lajaran membandingkan teks cerita pendek dengan teks eksplanasi kompleks pada siswa kelas X I SMA N 18 Bandung. M etode penelitian yang digunakan penulis dalam penelitian ini adalah me - tode penelitian one group pretest - posttest design, dengan teknik penelitian telaah pustaka, observasi, uji coba, dan tes. Adapun hasil penelitiannya sebagai berikut. 1. Penulis mampu merencanakan dan melaksanakan pembelajaran me mbanding - kan teks cerita pendek dengan teks eks planasi kompleks menggunakan m ode l c ooperative integrated reading and composition pada siswa kelas X I MIPA 4 SM AN 18 Bandung. Hal ini terbukti dengan hasil penilaian perencanaan dan pelaksanakan pembelajaran sebesar 3, 8 6 . Ke mampuan penulis termasuk ke d a - lam kategori sangat baik (A). 2. Siswa kelas X I MIPA 4 SMA N 18 B andung mampu me mbandingkan teks ceri - ta pendek dengan teks eksplanasi kompleks menggunakan m ode l cooperative integrated reading and composition . Hal ini terbukti dari nilai rata - rata pretes yaitu 0,91 , sedangkan nilai rata - rata postes 2,61 . Jadi selisih nilai rata - rat a pre tes dan post es yaitu 1,7 . 3. M ode l cooperative integrated reading and composition efektif digunakan da - lam me mbandingkan teks prosedur kom pleks pada siswa kelas X I MIPA 4 SM AN 18 Bandung. Hal ini terbukti dari hasil perhitungan taraf signifikan perbedaan dua mean antara pretes dengan nilai postes , diketahui t hitung 11,62 > t tabel 2,0 5 . Kata ku nci: Pembelajaran, membandingkan, teks cerita pendek , teks eksplanasi kompleks, cooperative integrated reading and composition

Valence transition in the periodic Anderson model

A very rich phase diagram has recently been found in CeCu$_{2}$Si$_{2}$ from high pressure experiments where, in particular, a transition between an intermediate valence configuration and an integral valent heavy fermion state has been observed. We show that such a valence transition can be understood in the framework of the periodic Anderson model. In particular, our results show a breakdown of a mixed-valence state which is accompanied by a drastic change in the \textit{f} occupation in agreement with experiment. This valence transition can possibly be interpreted as a collapse of the large Fermi surface of the heavy fermion state which incorporates not only the conduction electrons but also the localized \textit{f} electrons. The theoretical approach used in this paper is based on the novel projector-based renormalization method (PRM). With respect to the periodic Anderson model, the method was before only employed in combination with the basic approximations of the well-known slave-boson mean-field theory. In this paper, the PRM treatment is performed in a more sophisticated manner where both mixed as well as integral valent solutions have been obtained. Furthermore, we argue that the presented PRM approach might be a promising starting point to study the competing interactions in CeCu$_{2}$Si$_{2}$ and related compounds.Comment: 9 pages, 3 figures included; v2: completely revised and extended versio

Entanglement with phase decoherence

The system of an atom couples to two distinct optical cavities with phase decoherence is studied by making use of a dynamical algebraic method. We adopt the concurrence to characterize the entanglement between atom and cavities or between two optical cavities in the presence of the phase decoherence. It is found that the entanglement between atom and cavities can be controlled by adjusting the detuning parameter. Finally, we show that even if the atom is initially prepared in a maximally mixed state, it can also entangle the two mode cavity fields.Comment: 9 pages, 6 figures, lete

3D crystal: how flat its flat facets are?

We investigate the hypothesis that the (random) crystal of the $(-)$-phase inside the $(+)$-phase of the 3D canonical Ising model has flat facets. We argue that it might need to be weakened, due to the possibility of formation of extra monolayer on a facet. We then prove this weaker hypothesis for the Solid-On-Solid model

Non-perturbative Pion Matrix Element of a twist-2 operator from the Lattice

We give a continuum limit value of the lowest moment of a twist-2 operator in pion states from non-perturbative lattice calculations. We find that the non-perturbatively obtained renormalization group invariant matrix element is _{RGI} = 0.179(11), which corresponds to ^{MSbar}(2 GeV) = 0.246(15). In obtaining the renormalization group invariant matrix element, we have controlled important systematic errors that appear in typical lattice simulations, such as non-perturbative renormalization, finite size effects and effects of a non-vanishing lattice spacing. The crucial limitation of our calculation is the use of the quenched approximation. Another question that remains not fully clarified is the chiral extrapolation of the numerical data.Comment: 26 pages, 10 figures, v2: final version, accepted for publication in EPJ

Subjects : Spanish Pavilion, 56th International Art Exhibition la Biennale di Venezia.

Colabora en la publicación Cooperación EspañolaObra publicada con motivo de la exposición presentada en el Pabellón Español de la 56ª Bienal de Venecia, celebrada del 9 de mayo al 22 de noviembre de 2015El pabellón de España en la Bienal está organizado por la Dirección de Relaciones Culturales y Científicas del Ministerio de Asuntos Exteriores y Cooperación con la colaboración de Acción Cultural Española. El proyecto Los sujetos incluye obras de Pepo Salazar, Helena Cabello & Ana Carceller y Francesc Ruiz. Todos ellos pretenden aportar una visión muy libre de Dalí a través de sus obras: un diálogo directo que no quiere ser una ilustración del pasado desde el presente sino directamente un presente que permita resituar la creación, la identidad y una línea temporal desde el hoy, desde nuestra situación, desde la multiplicidad

Collins effect and single spin azimuthal asymmetries in the HERMES and COMPASS experiments

Predictions are made for single spin azimuthal asymmetries due to the Collins effect in pion production from semi-inclusive deeply inelastic scattering off transversely and longitudinally polarized targets for the HERMES and COMPASS experiments. The x-dependence of the asymmetries is evaluated using the parton distribution functions from the chiral quark-soliton model. The overall normalization of the predicted asymmetries is determined by the information on the Collins fragmentation function extracted from previous HERMES data on azimuthal asymmetries from a longitudinally polarized target. The single spin asymmetries from the transversely polarized proton target are found to be about 20% for positive and neutral pions both at HERMES and COMPASS. For a longitudinally polarized target we obtain for COMPASS a sin(phi) asymmetry of 1% and a sin(2phi) asymmetry of about 3%.Comment: 10 pages, 9 figures, Ref.[29] adde