From confined spinons to emergent fermions: Observation of elementary magnetic excitations in a transverse-field Ising chain

We report on spectroscopy study of elementary magnetic excitations in an Ising-like antiferromagnetic chain compound SrCo$_2$V$_2$O$_8$ as a function of temperature and applied transverse magnetic field up to 25 T. An optical as well as an acoustic branch of confined spinons, the elementary excitations at zero field, are identified in the antiferromagnetic phase below the N\'{e}el temperature of 5 K and described by a one-dimensional Schr\"{o}dinger equation. The confinement can be suppressed by an applied transverse field and a quantum disordered phase is induced at 7 T. In this disordered paramagnetic phase, we observe three emergent fermionic excitations with different transverse-field dependencies. The nature of these modes is clarified by studying spin dynamic structure factor of a 1D transverse-field Heisenberg-Ising (XXZ) model using the method of infinite time evolving block decimation. Our work reveals emergent quantum phenomena and provides a concrete system for testifying theoretical predications of one-dimension quantum spin models.Comment: 8 pages and 6 figure

Non-Abelian statistics in light scattering processes across interacting Haldane chains

The $S=1$ Haldane state is constructed from a product of local singlet dimers in the bulk and topological states at the edges of a chain. It is a fundamental representative of topological quantum matter. Its well-known representative, the quasi-one-dimensional SrNi$_2$V$_2$O$_8$ shows both conventional as well as unconventional magnetic Raman scattering. The former is observed as one- and two-triplet excitations with small linewidths and energies corresponding to the Haldane gap $\Delta_H$ and the exchange coupling $J_c$ along the chain, respectively. Well-defined magnetic quasiparticles are assumed to be stabilized by interchain interactions and uniaxial single-ion anisotropy. Unconventional scattering exists as broad continua of scattering with an intensity $I(T)$ that shows a mixed bosonic / fermionic statistic. Such a mixed statistic has also been observed in Kitaev spin liquids and could point to a non-Abelian symmetry. As the ground state in the bulk of SrNi$_2$V$_2$O$_8$ is topologically trivial, we suggest its fractionalization to be due to light-induced interchain exchange processes. These processes are supposed to be enhanced due to a proximity to an Ising ordered state with a quantum critical point. A comparison with SrCo$_2$V$_2$O$_8$, the $S=1/2$ analogue to our title compound, supports these statements.Comment: 3 figures, 1 tabl

Experimental observation of Bethe strings

Almost a century ago, string states-complex bound states of magnetic excitations-were predicted to exist in one-dimensional quantum magnets(1). However, despite many theoretical studies(2-11), the experimental realization and identification of string states in a condensed-matter system have yet to be achieved. Here we use high-resolution terahertz spectroscopy to resolve string states in the antiferromagnetic Heisenberg-Ising chain SrCo2V2O8 in strong longitudinal magnetic fields. In the field-induced quantum-critical regime, we identify strings and fractional magnetic excitations that are accurately described by the Bethe ansatz(1,3,4). Close to quantum criticality, the string excitations govern the quantum spin dynamics, whereas the fractional excitations, which are dominant at low energies, reflect the antiferromagnetic quantum fluctuations. Today, Bethe's result(1) is important not only in the field of quantum magnetism but also more broadly, including in the study of cold atoms and in string theory; hence, we anticipate that our work will shed light on the study of complex many-body systems in general

Laparoscopic ureteric reimplantation of a single-system ectopic ureter in a girl: A rarity

A 14-year-old girl presented with continuous dribbling of urine along with normal voiding pattern since childhood. Cystourethroscopy showed absence of right ureteric opening, and vaginoscopy showed right ureter opening into vaginal vault. Radiological images showed small right kidney with normal excretory function with single-system ectopic ureter. Patient underwent laparoscopic transperitoneal extravesical ureteric reimplantation. At 3 months′ follow-up, intravenous urography (IVU) and micturating cystourethrogram (MCU) showed no obstruction and reflux

Laparoscopic adrenalectomy: A single center experience

Aims : To evaluate the efficacy and safety of laparoscopic adrenalectomy in benign adrenal disorders. Methods and Material: Since July 2007, twenty patients have undergone laparoscopic adrenalectomy for various benign adrenal disorders at our institution. Every patient underwent contrast enhanced CT-abdomen. Serum corticosteroid levels were conducted in all, and urinary metanephrines, normetanephrines and VMA levels were performed in suspected pheochromocytoma. All the patients underwent laparoscopic adrenalectomy via the transperitoneal approach. Results : The patients were in the age range of 18-57 years, eleven males and nine females, seven right, eleven left, two bilateral. The mean operative time was 150 minutes (120-180), mean hospital stay four days (3-5), mean intraoperative blood loss 150 ml and mean post-operative analgesic need was for 36 (24-72) hours. One out of twenty-two laparoscopic operations had to be converted into open adrenalectomy due to intra-operative complications. Conclusions : Laparoscopic adrenalectomy is a safe, effective and useful procedure without any major post-operative complication and is the gold standard for all benign adrenal disorders

Time and magnetic field dependent magnetic order in Ca3_3Co2_2O6_6 revealed by resonant x-ray scattering

The observation of time dependent magnetic order in the spin-chain compound Ca$_3$Co$_2$O$_6$, a promising candidate for showing out-of-equilibrium magnetization behavior, has received tremendous attention for over a decade. The present study uses resonant magnetic scattering close to the cobalt K-absorption edge to probe directly the time, temperature, and magnetic field dependence of the magnetic order in a Ca$_3$Co$_2$O$_6$ single crystal. Energy dependences of the magnetic signal and their simulation suggest that the resonant x-ray scattering (RXS) signal at the pre-edge contains contributions only from quadrupole (E2E2) and dipolar-quadrupolar (E1E2) transition processes. Interestingly, the flat intensity variation as a function of azimuthal angle over a wide angular range cannot be explained by considering the ordering of magnetic dipole moments alone. The observed magnetic order below the Néel temperature $T_N$ in the present RXS study differs significantly from the reported neutron diffraction results, indicating possible contributions from high-order moments in addition to the magnetic dipole moment

Laparoscopic adrenalectomy: A single center experience

Aims : To evaluate the efficacy and safety of laparoscopic adrenalectomy in benign adrenal disorders. Methods and Material: Since July 2007, twenty patients have undergone laparoscopic adrenalectomy for various benign adrenal disorders at our institution. Every patient underwent contrast enhanced CT-abdomen. Serum corticosteroid levels were conducted in all, and urinary metanephrines, normetanephrines and VMA levels were performed in suspected pheochromocytoma. All the patients underwent laparoscopic adrenalectomy via the transperitoneal approach. Results : The patients were in the age range of 18-57 years, eleven males and nine females, seven right, eleven left, two bilateral. The mean operative time was 150 minutes (120-180), mean hospital stay four days (3-5), mean intraoperative blood loss 150 ml and mean post-operative analgesic need was for 36 (24-72) hours. One out of twenty-two laparoscopic operations had to be converted into open adrenalectomy due to intra-operative complications. Conclusions : Laparoscopic adrenalectomy is a safe, effective and useful procedure without any major post-operative complication and is the gold standard for all benign adrenal disorders

Oblique angle deposited FeCo multilayered nanocolumnar structure: magnetic anisotropy and its thermal stability in polycrystalline thin films

Iron-Cobalt (FeCo) columnar, multilayered structure is prepared by depositing several thin FeCo layers by varying the angle between the surface normal and the evaporation direction as 0° (normal) and 60°(oblique), alternatively. In situ X-ray scattering and magneto-optical Kerr effect (MOKE) measurements established the evolution of magnetic properties with that of the morphology and structure of the multilayer. The strong shape anisotropy and compressive stress of nanocolumns in alternative FeCo layers resulted in a well-defined uniaxial magnetic anisotropy (UMA) with the easy axis of magnetization along the projection of the tilted nanocolumns in the film plane. The stress in the film provides minimization of magnetoelastic energy along the in-plane column direction, which couples with the columnar shape anisotropy energies and results in the preferential orientation of the magnetic easy axis along the oblique angle deposition direction in the film plane. Drastic reduction in the in-plane UMA after annealing at 450 °C is attributed to the merging of columns and removal of stresses after heat treatment. The present study opens a new pathway to produce magnetically anisotropic multilayer structures using single material and thus may have prominent implications for future technological devices

Morphology induced large magnetic anisotropy in obliquely grown nanostructured thin film on nanopatterned substrate

The artificial tailoring of magnetic anisotropy by manipulating surface and interface morphology is attracting widespread interest for its application in spintronic and magnetic memory devices. Here oblique angle deposition on a nanopatterned rippled substrate is presented as a novel route of inducing large in-plane uniaxial magnetic anisotropy (UMA) in magnetic thin films. For this purpose, Cobalt films and rippled SiO$_2$ substrates have been taken as a model system for the present study. Here, nanopatterned substrates are prepared by low energy ion beam erosion (IBE), above which films are deposited obliquely along and normal to the ripple directions. A clear anisotropy in the growth behavior has been observed due to the inhomogeneous in-plane organization of adatoms in the form of columns. The increased shadowing effect in the films deposited obliquely normal to the direction of the ripple patterns causes preferential coalescence of the columns along the substrate ripples, resulting in stronger in-plane UMA in the film. This peculiarity in magnetic behavior is addressed by considering the morphological anisotropy governed by enhanced shadowing effect, the shape anisotropy and the dipolar interactions among the magnetostatically coupled ripple structure