Volume 91, Issue 6

1 February 2015

Browse Issues:

HIGHLIGHTED ARTICLES

EDITORS' SUGGESTION

RAPID COMMUNICATION

Controlled suppression of superconductivity by the generation of polarized Cooper pairs in spin-valve structures

M. G. Flokstra, T. C. Cunningham, J. Kim, N. Satchell, G. Burnell, P. J. Curran, S. J. Bending, C. J. Kinane, J. F. K. Cooper, S. Langridge, A. Isidori, N. Pugach, M. Eschrig, and S. L. Lee

Phys. Rev. B 91, 060501(R) (2015) - Published 2 February, 2015

The authors create an unconventional superconducting state in the vicinity of noncollinear ferromagnetic interfaces. In particular, they use Co spin-valve structures to modify the superconducting state of Nb, a conventional superconductor, by the controlled generation of equal spin superconducting triplets from the singlet ground state.

EDITORS' SUGGESTION

RAPID COMMUNICATION

High-temperature superconductivity stabilized by electron-hole interband coupling in collapsed tetragonal phase of ${KFe}_{2} {As}_{2}$ under high pressure

Yasuyuki Nakajima, Renxiong Wang, Tristin Metz, Xiangfeng Wang, Limin Wang, Hyunchae Cynn, Samuel T. Weir, Jason R. Jeffries, and Johnpierre Paglione

Phys. Rev. B 91, 060508(R) (2015) - Published 27 February, 2015

By investigating transport and structural properties of KFe $_{2}$ As $_{2}$ under pressures up to 33 GPa, this group reveals the presence of two superconducting phases that appear distinct, and each showing strong enhancements in their transition temperature as a function of pressure. The second, higher- $T_{c}$ phase abruptly appears upon collapse of the tetragonal structure at higher pressures.

EDITORS' SUGGESTION

Hidden order as a source of interface superconductivity

Andreas Moor, Anatoly F. Volkov, and Konstantin B. Efetov

Phys. Rev. B 91, 064511 (2015) - Published 27 February, 2015

In this work the authors present a novel mechanism for interfacial superconductivity which has been observed in many materials including high- $T_{c}$ superconductors. The suggested mechanism is based on an interplay between competing order parameters: superconducting order parameter, and charge- or spin-density wave.

RAPID COMMUNICATIONS

Structure, structural phase transitions, mechanical properties, defects

RAPID COMMUNICATION

Universal mechanism of thermomechanical deformation in metallic glasses

W. Dmowski, Y. Tong, T. Iwashita, Y. Yokoyama, and T. Egami

Phys. Rev. B 91, 060101(R) (2015) - Published 11 February, 2015

RAPID COMMUNICATION

Anomalously thick domain walls in ferroelectrics

P. V. Yudin, M. Y. Gureev, T. Sluka, A. K. Tagantsev, and N. Setter

Phys. Rev. B 91, 060102(R) (2015) - Published 18 February, 2015

Magnetism

RAPID COMMUNICATION

Charged skyrmions on the surface of a topological insulator

Hilary M. Hurst, Dmitry K. Efimkin, Jiadong Zang, and Victor Galitski

Phys. Rev. B 91, 060401(R) (2015) - Published 18 February, 2015

RAPID COMMUNICATION

Spin excitations in the two-dimensional strongly coupled dimer system malachite

E. Canévet, B. Fåk, R. K. Kremer, J. H. Chun, M. Enderle, E. E. Gordon, J. L. Bettis, M.-H. Whangbo, J. W. Taylor, and D. T. Adroja

Phys. Rev. B 91, 060402(R) (2015) - Published 20 February, 2015

RAPID COMMUNICATION

Simplex valence-bond crystal in the spin-1 kagome Heisenberg antiferromagnet

Tao Liu, Wei Li, Andreas Weichselbaum, Jan von Delft, and Gang Su

Phys. Rev. B 91, 060403(R) (2015) - Published 23 February, 2015

RAPID COMMUNICATION

Complex domain walls in ${BiFeO}_{3}$

Zukhra Gareeva, Oswaldo Diéguez, Jorge Íñiguez, and Anatoly K. Zvezdin

Phys. Rev. B 91, 060404(R) (2015) - Published 23 February, 2015

RAPID COMMUNICATION

In-plane field-driven crossover in the spin-torque mechanism acting on magnetic domain walls in Co/Ni

Kohei Ueda, Kab-Jin Kim, Takuya Taniguchi, Takayuki Tono, Takahiro Moriyama, and Teruo Ono

Phys. Rev. B 91, 060405(R) (2015) - Published 26 February, 2015

RAPID COMMUNICATION

Novel phase transition and metastable regions in the frustrated magnet ${CdCr}_{2} O_{4}$

S. Zherlitsyn, V. Tsurkan, A. A. Zvyagin, S. Yasin, S. Erfanifam, R. Beyer, M. Naumann, E. Green, J. Wosnitza, and A. Loidl

Phys. Rev. B 91, 060406(R) (2015) - Published 27 February, 2015

RAPID COMMUNICATION

Luttinger liquid behavior in the alternating spin-chain system copper nitrate

B. Willenberg, H. Ryll, K. Kiefer, D. A. Tennant, F. Groitl, K. Rolfs, P. Manuel, D. Khalyavin, K. C. Rule, A. U. B. Wolter, and S. Süllow

Phys. Rev. B 91, 060407(R) (2015) - Published 27 February, 2015

Superfluidity and superconductivity

EDITORS' SUGGESTION

RAPID COMMUNICATION

Controlled suppression of superconductivity by the generation of polarized Cooper pairs in spin-valve structures

M. G. Flokstra, T. C. Cunningham, J. Kim, N. Satchell, G. Burnell, P. J. Curran, S. J. Bending, C. J. Kinane, J. F. K. Cooper, S. Langridge, A. Isidori, N. Pugach, M. Eschrig, and S. L. Lee

Phys. Rev. B 91, 060501(R) (2015) - Published 2 February, 2015

RAPID COMMUNICATION

Robust superconductivity with nodes in the superconducting topological insulator ${Cu}_{x} {Bi}_{2} {Se}_{3}$ : Zeeman orbital field and nonmagnetic impurities

Yuki Nagai

Phys. Rev. B 91, 060502(R) (2015) - Published 5 February, 2015

RAPID COMMUNICATION

Broken time-reversal symmetry probed by muon spin relaxation in the caged type superconductor ${Lu}_{5} {Rh}_{6} {Sn}_{18}$

A. Bhattacharyya, D. T. Adroja, J. Quintanilla, A. D. Hillier, N. Kase, A. M. Strydom, and J. Akimitsu

Phys. Rev. B 91, 060503(R) (2015) - Published 10 February, 2015

RAPID COMMUNICATION

Local characterization of superconductivity in $BaF e_{2} {(A s_{1 - x} P_{x})}_{2}$

Y. Lamhot, A. Yagil, N. Shapira, S. Kasahara, T. Watashige, T. Shibauchi, Y. Matsuda, and O. M. Auslaender

Phys. Rev. B 91, 060504(R) (2015) - Published 12 February, 2015

RAPID COMMUNICATION

Spin reorientation in ${Ba}_{0.65} {Na}_{0.35} {Fe}_{2} {As}_{2}$ studied by single-crystal neutron diffraction

F. Waßer, A. Schneidewind, Y. Sidis, S. Wurmehl, S. Aswartham, B. Büchner, and M. Braden

Phys. Rev. B 91, 060505(R) (2015) - Published 19 February, 2015

RAPID COMMUNICATION

Frequency dispersion of nonlinear response of thin superconducting films in the Berezinskii-Kosterlitz-Thouless state

Scott Dietrich, William Mayer, Sean Byrnes, Sergey Vitkalov, A. Sergeev, Anthony T. Bollinger, and Ivan Božović

Phys. Rev. B 91, 060506(R) (2015) - Published 20 February, 2015

RAPID COMMUNICATION

Ray optics behavior of flux avalanche propagation in superconducting films

P. Mikheenko, T. H. Johansen, S. Chaudhuri, I. J. Maasilta, and Y. M. Galperin

Phys. Rev. B 91, 060507(R) (2015) - Published 23 February, 2015

EDITORS' SUGGESTION

RAPID COMMUNICATION

High-temperature superconductivity stabilized by electron-hole interband coupling in collapsed tetragonal phase of ${KFe}_{2} {As}_{2}$ under high pressure

Yasuyuki Nakajima, Renxiong Wang, Tristin Metz, Xiangfeng Wang, Limin Wang, Hyunchae Cynn, Samuel T. Weir, Jason R. Jeffries, and Johnpierre Paglione

Phys. Rev. B 91, 060508(R) (2015) - Published 27 February, 2015

RAPID COMMUNICATION

Visualizing superconductivity in FeSe nanoflakes on ${SrTiO}_{3}$ by scanning tunneling microscopy

Zhi Li, Jun-Ping Peng, Hui-Min Zhang, Can-Li Song, Shuai-Hua Ji, Lili Wang, Ke He, Xi Chen, Qi-Kun Xue, and Xu-Cun Ma

Phys. Rev. B 91, 060509(R) (2015) - Published 27 February, 2015

RAPID COMMUNICATION

Coexistence of multiple charge-density waves and superconductivity in ${SrPt}_{2} {As}_{2}$ revealed by ${}^{75}{As} - NMR / NQR$ and ${}^{195}{Pt} - NMR$

Shinji Kawasaki, Yoshihiko Tani, Tomosuke Mabuchi, Kazutaka Kudo, Yoshihiro Nishikubo, Daisuke Mitsuoka, Minoru Nohara, and Guo-qing Zheng

Phys. Rev. B 91, 060510(R) (2015) - Published 27 February, 2015

RAPID COMMUNICATION

What superconducts in sulfur hydrides under pressure and why

N. Bernstein, C. Stephen Hellberg, M. D. Johannes, I. I. Mazin, and M. J. Mehl

Phys. Rev. B 91, 060511(R) (2015) - Published 27 February, 2015

RAPID COMMUNICATION

Polar Kerr effect from a time-reversal symmetry breaking unidirectional charge density wave

M. Gradhand, I. Eremin, and J. Knolle

Phys. Rev. B 91, 060512(R) (2015) - Published 27 February, 2015

RAPID COMMUNICATION

Role of chalcogen vapor annealing in inducing bulk superconductivity in ${Fe}_{1 + y} {Te}_{1 - x} {Se}_{x}$

Wenzhi Lin, P. Ganesh, Anthony Gianfrancesco, Jun Wang, Tom Berlijn, Thomas A. Maier, Sergei V. Kalinin, Brian C. Sales, and Minghu Pan

Phys. Rev. B 91, 060513(R) (2015) - Published 27 February, 2015

ARTICLES

Structure, structural phase transitions, mechanical properties, defects

X-ray study of metal-insulator transitions induced by W doping and photoirradiation in ${VO}_{2}$ films

D. Okuyama, K. Shibuya, R. Kumai, T. Suzuki, Y. Yamasaki, H. Nakao, Y. Murakami, M. Kawasaki, Y. Taguchi, Y. Tokura, and T. Arima

Phys. Rev. B 91, 064101 (2015) - Published 3 February, 2015

Superior magnetic and mechanical property of ${MnFe}_{3} N$ driven by electron correlation and lattice anharmonicity

Hao Wu, Hong Sun, and Changfeng Chen

Phys. Rev. B 91, 064102 (2015) - Published 5 February, 2015

Point defect stability in a semicoherent metallic interface

C. González, R. Iglesias, and M. J. Demkowicz

Phys. Rev. B 91, 064103 (2015) - Published 11 February, 2015

Metallic ferroelectricity induced by anisotropic unscreened Coulomb interaction in ${LiOsO}_{3}$

H. M. Liu, Y. P. Du, Y. L. Xie, J.-M. Liu, Chun-Gang Duan, and Xiangang Wan

Phys. Rev. B 91, 064104 (2015) - Published 20 February, 2015

Cooling rates dependence of medium-range order development in $C u_{64.5} Z r_{35.5}$ metallic glass

Y. Zhang, F. Zhang, C. Z. Wang, M. I. Mendelev, M. J. Kramer, and K. M. Ho

Phys. Rev. B 91, 064105 (2015) - Published 23 February, 2015

Inhomogeneous, disordered, and partially ordered systems

Topological pumping over a photonic Fibonacci quasicrystal

Mor Verbin, Oded Zilberberg, Yoav Lahini, Yaacov E. Kraus, and Yaron Silberberg

Phys. Rev. B 91, 064201 (2015) - Published 4 February, 2015

Infinite volume extrapolation in the one-dimensional bond diluted Levy spin-glass model near its lower critical dimension

L. Leuzzi, G. Parisi, F. Ricci-Tersenghi, and J. J. Ruiz-Lorenzo

Phys. Rev. B 91, 064202 (2015) - Published 5 February, 2015

Echo spectroscopy of Anderson localization

T. Micklitz, C. A. Müller, and A. Altland

Phys. Rev. B 91, 064203 (2015) - Published 23 February, 2015

Dynamics, dynamical systems, lattice effects

Neutron inelastic scattering measurements of low-energy phonons in the multiferroic ${BiFeO}_{3}$

John A. Schneeloch, Zhijun Xu, Jinsheng Wen, P. M. Gehring, C. Stock, M. Matsuda, B. Winn, Genda Gu, Stephen M. Shapiro, R. J. Birgeneau, T. Ushiyama, Y. Yanagisawa, Y. Tomioka, T. Ito, and Guangyong Xu

Phys. Rev. B 91, 064301 (2015) - Published 10 February, 2015

Semiclassical analysis of high harmonic generation in bulk crystals

G. Vampa, C. R. McDonald, G. Orlando, P. B. Corkum, and T. Brabec

Phys. Rev. B 91, 064302 (2015) - Published 23 February, 2015

Lattice dynamics of ${BaFe}_{2} X_{3} (X = S, Se)$ compounds

Z. V. Popović, M. Šćepanović, N. Lazarević, M. Opačić, M. M. Radonjić, D. Tanasković, Hechang Lei (雷和畅), and C. Petrovic

Phys. Rev. B 91, 064303 (2015) - Published 27 February, 2015

Simple view of the ${Mg}_{2} {Si}_{1 - x} {Sn}_{x}$ phonon spectrum: Sn resonances and mean field

Laurent Chaput, Julie Bourgeois, Anastasiia Prytuliak, Michael Marek Koza, and Hubert Scherrer

Phys. Rev. B 91, 064304 (2015) - Published 27 February, 2015

Local density of states on a vibrational quantum dot out of equilibrium

K. F. Albrecht, A. Martin-Rodero, J. Schachenmayer, and L. Mühlbacher

Phys. Rev. B 91, 064305 (2015) - Published 27 February, 2015

Magnetism

Order induced by dilution in pyrochlore XY antiferromagnets

A. Andreanov and P. A. McClarty

Phys. Rev. B 91, 064401 (2015) - Published 2 February, 2015

Thermal properties of a spin spiral: Manganese on tungsten(110)

G. Hasselberg, R. Yanes, D. Hinzke, P. Sessi, M. Bode, L. Szunyogh, and U. Nowak

Phys. Rev. B 91, 064402 (2015) - Published 2 February, 2015

Low-temperature resistivity, magnetoresistance, and domain-wall resistance of highly pure single- and polycrystalline iron

Dieter Elefant and Rudolf Schäfer

Phys. Rev. B 91, 064403 (2015) - Published 2 February, 2015

Diluted orbital degeneracy and large orthorhombic distortions in ferrimagnetic spinel ${Cu}_{x} {Mn}_{3 - x} O_{4}$

Kee Hwan Lee, Hun Chang, In Yong Hwang, Jae-Ho Chung, Hyun Wook Kang, Su Jae Kim, and Seongsu Lee

Phys. Rev. B 91, 064404 (2015) - Published 3 February, 2015

Variations of magnetic properties of ${UGa}_{2}$ under pressure

A. V. Kolomiets, J.-C. Griveau, J. Prchal, A. V. Andreev, and L. Havela

Phys. Rev. B 91, 064405 (2015) - Published 3 February, 2015

Theory of magnetic phase diagrams in hyperhoneycomb and harmonic-honeycomb iridates

Eric Kin-Ho Lee and Yong Baek Kim

Phys. Rev. B 91, 064407 (2015) - Published 4 February, 2015

Incommensurate magnetic structure, Fe/Cu chemical disorder, and magnetic interactions in the high-temperature multiferroic $YBaCuFeO_{5}$

M. Morin, A. Scaramucci, M. Bartkowiak, E. Pomjakushina, G. Deng, D. Sheptyakov, L. Keller, J. Rodriguez-Carvajal, N. A. Spaldin, M. Kenzelmann, K. Conder, and M. Medarde

Phys. Rev. B 91, 064408 (2015) - Published 6 February, 2015

Stabilizing and increasing the magnetic moment of half-metals: The role of Li in half-Heusler $LiMn Z$ $(Z = N, P, Si)$

L. Damewood, B. Busemeyer, M. Shaughnessy, C. Y. Fong, L. H. Yang, and C. Felser

Phys. Rev. B 91, 064409 (2015) - Published 6 February, 2015

Magnetic exchange coupling in $IrMn / NiFe$ nanostructures: From the continuous film to dot arrays

F. Spizzo, E. Bonfiglioli, M. Tamisari, A. Gerardino, G. Barucca, A. Notargiacomo, F. Chinni, and L. Del Bianco

Phys. Rev. B 91, 064410 (2015) - Published 6 February, 2015

Selection of factorizable ground state in a frustrated spin tube: Order by disorder and hidden ferromagnetism

X. Plat, Y. Fuji, S. Capponi, and P. Pujol

Phys. Rev. B 91, 064411 (2015) - Published 6 February, 2015

Controlling the spin-torque efficiency with ferroelectric barriers

A. Useinov, M. Chshiev, and A. Manchon

Phys. Rev. B 91, 064412 (2015) - Published 11 February, 2015

Magnetically disordered phase in epitaxial iron-deficient $F e_{3} O_{4}$ thin films

J. A. Moyer, S. Lee, P. Schiffer, and L. W. Martin

Phys. Rev. B 91, 064413 (2015) - Published 13 February, 2015

Local structural distortions, orbital ordering, and ferromagnetism in underdoped ${La}_{1 - x} {Sr}_{x} {MnO}_{3}$

J.-S. Zhou and J. B. Goodenough

Phys. Rev. B 91, 064414 (2015) - Published 17 February, 2015

Nematic and supernematic phases in kagome quantum antiferromagnets under the influence of a magnetic field

Thibaut Picot and Didier Poilblanc

Phys. Rev. B 91, 064415 (2015) - Published 17 February, 2015

Control of spin-wave excitations in deterministic fractals

Christian Swoboda, Michael Martens, and Guido Meier

Phys. Rev. B 91, 064416 (2015) - Published 17 February, 2015

Spin-wave multiple excitations in nanoscale classical Heisenberg antiferromagnets

Zhuofei Hou, D. P. Landau, G. M. Stocks, and G. Brown

Phys. Rev. B 91, 064417 (2015) - Published 17 February, 2015

Spin reorientation and Ce-Mn coupling in antiferromagnetic oxypnictide CeMnAsO

Qiang Zhang, Wei Tian, Spencer G. Peterson, Kevin W. Dennis, and David Vaknin

Phys. Rev. B 91, 064418 (2015) - Published 18 February, 2015

Evidence for a hybridization gap in noncentrosymmetric ${CeRuSi}_{3}$

M. Smidman, D. T. Adroja, E. A. Goremychkin, M. R. Lees, D. M. Paul, and G. Balakrishnan

Phys. Rev. B 91, 064419 (2015) - Published 19 February, 2015

Spin-dependent polaron formation dynamics in ${Eu}_{0.75} Y_{0.25} {MnO}_{3}$ probed by femtosecond pump-probe spectroscopy

D. Talbayev, Jinho Lee, S. A. Trugman, C. L. Zhang, S.-W. Cheong, R. D. Averitt, A. J. Taylor, and R. P. Prasankumar

Phys. Rev. B 91, 064420 (2015) - Published 19 February, 2015

Nuclear magnetic resonance study of thin ${Co}_{2} {FeAl}_{0.5} {Si}_{0.5}$ Heusler films with varying thickness

A. Alfonsov, B. Peters, F. Y. Yang, B. Büchner, and S. Wurmehl

Phys. Rev. B 91, 064421 (2015) - Published 20 February, 2015

First-principles study of structurally modulated multiferroic ${CaMn}_{7} O_{12}$

Kun Cao, Roger D. Johnson, Natasha Perks, Feliciano Giustino, and Paolo G. Radaelli

Phys. Rev. B 91, 064422 (2015) - Published 27 February, 2015

Ultrafast switching of antiferromagnets via spin-transfer torque

Ran Cheng, Matthew W. Daniels, Jian-Gang Zhu, and Di Xiao

Phys. Rev. B 91, 064423 (2015) - Published 27 February, 2015

Spin excitations in the nematic phase and the metallic stripe spin-density wave phase of iron pnictides

M. Kovacic, M. H. Christensen, M. N. Gastiasoro, and B. M. Andersen

Phys. Rev. B 91, 064424 (2015) - Published 27 February, 2015

Competition between the inter- and intra-sublattice interactions in ${Yb}_{2} V_{2} O_{7}$

Z. L. Dun, J. Ma, H. B. Cao, Y. Qiu, J. R. D. Copley, T. Hong, M. Matsuda, J. G. Cheng, M. Lee, E. S. Choi, S. Johnston, and H. D. Zhou

Phys. Rev. B 91, 064425 (2015) - Published 27 February, 2015

Nonlinear ferromagnetic resonance shift in submicron Permalloy ellipses

Feng Guo, Lyubov M. Belova, and Robert D. McMichael

Phys. Rev. B 91, 064426 (2015) - Published 27 February, 2015

Unified molecular field theory for collinear and noncollinear Heisenberg antiferromagnets

David C. Johnston

Phys. Rev. B 91, 064427 (2015) - Published 27 February, 2015

Generalized mean-field description of entanglement in dimerized spin systems

A. Boette, R. Rossignoli, N. Canosa, and J. M. Matera

Phys. Rev. B 91, 064428 (2015) - Published 27 February, 2015

Superfluidity and superconductivity

Two-impurity helical Majorana problem

Erik Eriksson, Alex Zazunov, Pasquale Sodano, and Reinhold Egger

Phys. Rev. B 91, 064501 (2015) - Published 11 February, 2015

Topological properties of helical Shiba chains with general impurity strength and hybridization

Alex Westström, Kim Pöyhönen, and Teemu Ojanen

Phys. Rev. B 91, 064502 (2015) - Published 11 February, 2015

Creation of quantum error correcting codes in the ultrastrong coupling regime

T. H. Kyaw, D. A. Herrera-Martí, E. Solano, G. Romero, and L.-C. Kwek

Phys. Rev. B 91, 064503 (2015) - Published 12 February, 2015

Enhancement of thermoelectric effect in diffusive superconducting bilayers with magnetic interfaces

Mikhail S. Kalenkov and Andrei D. Zaikin

Phys. Rev. B 91, 064504 (2015) - Published 13 February, 2015

Topological Yu-Shiba-Rusinov chain from spin-orbit coupling

P. M. R. Brydon, S. Das Sarma, Hoi-Yin Hui, and Jay D. Sau

Phys. Rev. B 91, 064505 (2015) - Published 17 February, 2015

Magnetic ground state of superconducting $Eu (Fe_{0.88} Ir_{0.12})_{2} As_{2}$ : A combined neutron diffraction and first-principles calculation study

W. T. Jin, Wei Li, Y. Su, S. Nandi, Y. Xiao, W. H. Jiao, M. Meven, A. P. Sazonov, E. Feng, Yan Chen, C. S. Ting, G. H. Cao, and Th. Brückel

Phys. Rev. B 91, 064506 (2015) - Published 17 February, 2015

Pairing gaps near ferromagnetic quantum critical points

M. Einenkel, H. Meier, C. Pépin, and K. B. Efetov

Phys. Rev. B 91, 064507 (2015) - Published 17 February, 2015

Effective theory of two-dimensional chiral superfluids: Gauge duality and Newton-Cartan formulation

Sergej Moroz and Carlos Hoyos

Phys. Rev. B 91, 064508 (2015) - Published 19 February, 2015

Quantum critical behavior in heavily doped ${LaFeAsO}_{1 - x} H_{x}$ pnictide superconductors analyzed using nuclear magnetic resonance

R. Sakurai, N. Fujiwara, N. Kawaguchi, Y. Yamakawa, H. Kontani, S. Iimura, S. Matsuishi, and H. Hosono

Phys. Rev. B 91, 064509 (2015) - Published 19 February, 2015

Enhancement of superconductivity in ${La}_{1 - x} {Sm}_{x} O_{0.5} F_{0.5} {BiS}_{2}$

Y. Fang, D. Yazici, B. D. White, and M. B. Maple

Phys. Rev. B 91, 064510 (2015) - Published 24 February, 2015

EDITORS' SUGGESTION