G. J. MacDougall

Study of the ground state properties of $LiHo_xY_{1-x}F_4$ using $\mu$SR (2009)

Rodriguez, J., Aczel, A. A., Carlo, J. P., Dunsiger, S. R., MacDougall, G. J., Russo, P. L., ...

$LiHo_xY_{1-x}F_4$ is an insulating system where the magnetic Ho$^{3+}$ ions have an Ising character, and interact mainly through magnetic dipolar fields. We used the muon spin relaxation technique...

Evolution of spin excitations into the superconducting state in FeTe1-xSex (2009)

Lumsden, M. D., Christianson, A. D., Goremychkin, E. A., Nagler, S. E., Mook, H. A., Stone, M. B., ...

The nature of the superconducting state in the recently discovered Fe-based superconductors1-3 is the subject of intense scrutiny. Neutron scattering investigations have already elucidated a strong...

Static and Dynamic Magnetism in Underdoped Superconductor BaFe$_{1.92}$Co$_{0.08}$As$_2$ (2009)

Christianson, A. D., Lumsden, M. D., Nagler, S. E., MacDougall, G. J., McGuire, M. A., Sefat, A. S., ...

We report neutron scattering measurements on single crystals of BaFe$_{1.92}$Co$_{0.08}$As$_2$. The magnetic Bragg peak intensity is reduced by 6 % upon cooling through T$_C$. The spin dynamics...

Two-dimensional resonant magnetic excitation in BaFe1.84Co0.16As2 (2008)

Lumsden, M. D., Christianson, A. D., Parshall, D., Stone, M. B., Nagler, S. E., MacDougall, G. J., ...

Inelastic neutron scattering measurements on single crystals of superconducting BaFe1.84Co0.16As2 reveal a magnetic excitation located at wavevectors (1/2 1/2 L) in tetragonal notation. On cooling...

Itinerant spin excitations near the hidden order transition in URu2Si2 (2008)

Janik, J. A., Zhou, H. D., Balicas, L., MacDougall, G. J., Luke, G. M., ...

By means of neutron scattering we show that the high-temperature precursor to the hidden order state of the heavy fermion superconductor URu$_{2}$Si$_{2}$ exhibits heavily damped incommensurate...

$\mu$SR studies of the frustrated quasi-2d square-lattice spin system Cu(Cl,Br)La(Nb,Ta)$_{2}$O$_{7}$: evolution from spin-gap to antiferromagnetic state (2008)

Uemura, Y. J., Aczel, A. A., Ajiro, Y., Carlo, J. P., Goko, T., Goldfeld, D. A., ...

We report muon spin relaxation ($\mu$SR) and magnetic susceptibility measurements on Cu(Cl,Br)La(Nb,Ta)$_{2}$O$_{7}$, which demonstrate: (a) the absence of static magnetism in (CuCl)LaNb$_{2}$O$_{7}$...

Signatures of Heterogeneous Magnetism in Overdoped La2-xSrxCuO4 from Muon Spin Rotation (2008)

MacDougall, G. J., Aczel, A. A., Birgeneau, R. J., Ito, T., Kim, H., ...

We present TF-\mu SR data on heavily overdoped La2-xSrxCuO4, which show a large, field-induced broadening of the local magnetic field distribution up to high temperatures well above T_{c}. The doping...

MuSR studies of RE(O,F)FeAs (RE = La, Nd, Ce) and LaOFeP systems: possible incommensurate/stripe magnetism and superfluid density (2008)

Carlo, J. P., Uemura, Y. J., Goko, T., MacDougall, G. J., Rodriguez, J. A., Yu, W., ...

Muon spin relaxation (MuSR) measurements in iron oxy-pnictide systems have revealed: (1) commensurate long-range order in undoped LaOFeAs; (2) Bessel function line shape in La(O0.97F0.03)FeAs which...

Absence of time reversal symmetry breaking in La_{2-x}Sr_{x}CuO_{4} (2008)

MacDougall, G. J., Aczel, A. A., Carlo, J. P., Ito, T., Rodriguez, J., Russo, P. L., ...

We have performed zero-field muon spin rotation measurements on single crystals of La_{2-x}Sr_{x}CuO_{4} to search for spontaneous currents in the pseudo-gap state. By comparing measurements on...

Gapped itinerant spin excitations account for missing entropy in the hidden order state of URu$_2$Si$_2$ (2007)

Wiebe, C. R., Janik, J. A., Macdougall, G. J., Luke, G. M., Garrett, J. D., Zhou, H. D., ...

One of the primary goals of modern condensed matter physics is to elucidate the nature of the ground state in various electronic systems. Many correlated electron materials, such as high temperature...

Impurity-induced singlet breaking in SrCu2(BO3)2 (2007)

Aczel, A. A., MacDougall, G. J., Rodriguez, J. A., Luke, G. M., Russo, P. L., Savici, A. T., ...

We have performed $\mu$SR studies on single crystals of SrCu$_2$(BO$_3$)$_2$, a quasi-two-dimensional spin system with a spin singlet ground state. We observe two different muon sites which we...

Phase separation and suppression of critical dynamics at quantum transitions of itinerant magnets: MnSi and (Sr$_{1-x}$Ca$_{x}$)RuO$_{3}$ (2006)

Uemura, Y. J., Goko, T., Gat-Malureanu, I. M., Carlo, J. P., Russo, P. L., Savici, A. T., ...

Quantum phase transitions (QPTs) have been studied extensively in correlated electron systems. Characterization of magnetism at QPTs has, however, been limited by the volume-integrated feature of...

2D Kagome Ordering in the 3D Frustrated Spinel Li2Mn2O4 (2005)

Wiebe, C. R., Russo, P. L., Savici, A. T., Uemura, Y. J., MacDougall, G. J., Luke, G. M., ...

muSR experiments on the geometrically frustrated spinel oxide, Li2Mn2O4, show the development of spin correlations over a range of length scales with decreasing temperature. Increased relaxation...

Muon Spin Relaxation Studies of Magnetic-Field-Induced Effects in High-$T_{c}$ Superconductors (2004)

Savici, A. T., Fukaya, A., Gat-Malureanu, I. M., Ito, T., Russo, P. L., Uemura, Y. J., ...

Muon spin relaxation ($\mu$SR) measurements in high transverse magnetic fields ($\parallel \hat c$) revealed strong field-induced quasi-static magnetism in the underdoped and Eu doped...

Unconventional superconductivity in Na$_{0.35}$CoO$_{2}\cdot$1.3D$_{2}$O and proximity to a magnetically ordered phase (2004)

Uemura, Y. J., Russo, P. L., Savici, A. T., Wiebe, C. R., MacDougall, G. J., Luke, G. M., ...

Muon spin relaxation ($\mu$SR) measurements on the new layered cobalt oxide superconductor Na$_{0.35}$CoO$_{2}\cdot$1.3H$_{2}$O and its parent, non-superconducting compounds, have revealed...