M. B. Maple

University of California, San Diego, San Diego, California, United States

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Publications (848)1393.97 Total impact

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    ABSTRACT: Magnetization measurements for magnetic fields [Formula: see text] up to 60 T are reported for the noncentrosymmetric spin-chain metal Yb2Fe12P7. These measurements reveal behavior that is consistent with Ising-like spin chain magnetism that produces pronounced spin degeneracy. In particular, we find that although a Brillouin field dependence is observed in M(H) for [Formula: see text] with a saturation moment that is close to the expected value for free ions of Yb(3+) , non-Brillouin-like behavior is seen for [Formula: see text] with an initial saturation moment that is nearly half the free ion value. In addition, hysteretic behavior that extends above the ordering temperature [Formula: see text] is seen for [Formula: see text] but not for [Formula: see text], suggesting out-of-equilibrium physics. This point of view is strengthened by the observation of a spin reconfiguration in the ordered state for [Formula: see text] which is only seen for [Formula: see text] and after polarizing the spins. Together with the heat capacity data, these results suggest that the anomalous low temperature phenomena that were previously reported (Baumbach 2010 et al Phys. Rev. Lett. 105 106403) are driven by spin degeneracy that is related to the Ising-like one dimensional chain-like configuration of the Yb ions.
    No preview · Article · Feb 2016 · Journal of Physics Condensed Matter
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    ABSTRACT: We report 29Si nuclear magnetic resonance measurements of single crystals and aligned powders of URu2Si2 under pressure in the hidden order and paramagnetic phases. We find that the Knight shift decreases with applied pressure, consistent with previous measurements of the static magnetic susceptibility. Previous measurements of the spin lattice relaxation time revealed a partial suppression of the density of states below 30 K. This suppression persists under pressure, and the onset temperature is mildly enhanced.
    No preview · Article · Dec 2015 · Physica B Condensed Matter
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    ABSTRACT: For a decade and a half, CeCoIn$_5$ and related alloys have served as a rich playground to explore the interplay between magnetism and unconventional superconductivity. Despite this extended study, the presence/absence of metamagnetism (MM) in this ternary system remains as an unresolved issue. Here we show that the linear and non-linear magnetic response in CeMIn$_5$ (M = Rh, Ir and Co) can be understood within the context of the recently proposed single energy scale (SES) model of MM. New measurements of the third-order susceptibility, $\chi_3$, in CeCoIn$_5$ are presented and together with the known systematics of the linear susceptibility in all three compounds, are shown to be consistent with the SES model. Predictions are made for the MM critical field in CeCoIn$_5$ and the fifth-order susceptibility, $\chi_5$.
    No preview · Article · Oct 2015
  • Y. Fang · D. Yazici · B. D. White · M. B. Maple

    No preview · Article · Sep 2015 · Physical Review B
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    ABSTRACT: We have found that the erbium magnetic moment is so large that in ErRhâBâ it can relax muon polarization in times shorter than can be resolved by a typical ..mu..SR apparatus. The complete relaxation signal is resolved at temperatures above 50K only because of rapid fluctuation of the erbium moment, which partially decouples it from the muon's moment. Not much signal is resolved at temperatures less than or equal to 10K, but no dramatic effect is seen in crossing the superconducting transition temperature. The higher temperature local field fluctuation rates observed appear consistent with the exchange and spin-lattice fluctuation rates to be expected of erbium in this material. Perhaps more information on moment dynamics below 10K can be obtained by alloying erbium with a nonmagnetic rare earth such as yttrium within the RERhâBâ structure (as has been attempted for holmium), to reduce the rms local field at the muon.
    No preview · Article · Jul 2015
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    ABSTRACT: We report the physical properties of single crystals of the compounds CeT2Cd20 (T = Ni, Pd) that were grown in a molten Cd flux. Large separations of ∼6.7-6.8 Å between Ce ions favor the localized magnetic moments that are observed in measurements of the magnetization. The strength of the Ruderman-Kittel-Kasuya-Yosida magnetic exchange interaction between the localized moments is severely limited by the large Ce-Ce separations and by weak hybridization between localized Ce 4 f and itinerant electron states. Measurements of electrical resistivity performed down to 0.138 K were unable to observe evidence for the emergence of magnetic order; however, magnetically-ordered ground states with very low transition temperatures are still expected in these compounds despite the isolated nature of the localized magnetic moments. Such a fragile magnetic order could be highly susceptible to tuning via applied pressure, but evidence for the emergence of magnetic order has not been observed so far in our measurements up to 2.5 GPa.
    No preview · Article · Jul 2015 · Journal of Physics Condensed Matter
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    Y. Fang · D. Yazici · B. D. White · M. B. Maple
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    ABSTRACT: Electrical resistivity measurements on La$_{1-x}$Sm$_{x}$O$_{0.5}$F$_{0.5}$BiS$_{2}$ ($x$ = 0.1, 0.3, 0.6, 0.8) have been performed under applied pressures up to 2.6 GPa from 2 K to room temperature. The superconducting transition temperature $T$$_{c}$ of each sample significantly increases at a Sm-concentration dependent pressure $P$$_{\rm t}$, indicating a pressure-induced phase transition from a low-$T$$_{c}$ to a high-$T$$_{c}$ phase. The compounds that have higher Sm concentrations have higher $T$$_{c}$ values at ambient pressure; however, the $T$$_{c}$ values at $P$ $>$ $P$$_{\rm t}$ decrease with $x$ and $P$$_{\rm t}$ shifts to higher pressures with Sm substitution. In the normal state, semiconducting-like behavior is suppressed and metallic conduction is induced with increasing pressure in all of the samples. These results suggest that the pressure dependence of $T$$_{c}$ for the BiS$_{2}$-based superconductors is related to the lattice parameters at ambient pressure and enable us to estimate the evolution of $T$$_{c}$ for SmO$_{0.5}$F$_{0.5}$BiS$_{2}$ under pressure.
    Full-text · Article · Jul 2015
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    ABSTRACT: Abstract La3Co4Sn13 and La3Ru4Sn13 were categorized as BCS superconductors. In a plot of the critical field Hc2 vs T, La3Ru4Sn13 displays a second superconducting phase at the higher critical temperature Tc, characteristic of inhomogeneous superconductors, while La3Co4Sn13 shows bulk superconductivity below Tc. We observe a decrease in critical temperatures with external pressure and magnetic field for both compounds. Additionally, for La3Ru4Sn13 we find that dTc/dP>dTc/dP. The pressure dependences of Tc are interpreted according to the McMillan theory and understood to be a consequence of lattice stiffening. The investigation of the superconducting state of La3CoxRu4-xSn13 shows a Tc that is larger then Tc for x < 4. This unique and unexpected observation is discussed as a result of the local disorder and/or the effect of chemical pressure when Ru atoms are partially replaced by smaller Co atoms.
    No preview · Article · Jul 2015 · Journal of Alloys and Compounds
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    ABSTRACT: The low temperature hidden order state of URu$_2$Si$_2$ has long been a subject of intense speculation, and is thought to represent an as yet undetermined many-body quantum state not realized by other known materials. Here, X-ray absorption spectroscopy (XAS) and high resolution resonant inelastic X-ray scattering (RIXS) are used to observe electronic excitation spectra of URu$_2$Si$_2$, as a means to identify the degrees of freedom available to constitute the hidden order wavefunction. Excitations are shown to have symmetries that derive from a correlated $5f^2$ atomic multiplet basis that is modified by itinerancy. The features, amplitude and temperature dependence of linear dichroism are in agreement with ground states that closely resemble the doublet $\Gamma_5$ crystal field state of uranium.
    No preview · Article · Jun 2015 · Physical Review Letters
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    ABSTRACT: We present electrical resistivity and ac-susceptibility measurements of GdTe$_3$, TbTe$_3$ and DyTe$_3$ performed under pressure. An upper charge-density-wave (CDW) is suppressed at a rate of $\mathrm{d}T_{\mathrm{CDW,1}}/\mathrm{d}P$ = $-$85 K/GPa. For TbTe$_3$ and DyTe$_3$, a second CDW below $T_{\mathrm{CDW,2}}$ increases with pressure until it reaches the $T_{\mathrm{CDW,1}}$($P$) line. For GdTe$_3$, the lower CDW emerges as pressure is increased above $\sim$ 1 GPa. As these two CDW states are suppressed with pressure, superconductivity (SC) appears in the three compounds at lower temperatures. Ac-susceptibility experiments performed on TbTe$_3$ provide compelling evidence for bulk SC in the low-pressure region of the phase diagram. We provide measurements of superconducting critical fields and discuss the origin of a high-pressure superconducting phase occurring above 5 GPa.
    Full-text · Article · Apr 2015 · Physical Review B
  • F Bridges · P Nast · J Wilde · T Keiber · M B Maple · K Huang · B D White
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    ABSTRACT: We investigated the local structure of the Sb doped skutterudite CePt4Ge12-x Sbx using the Extended X-ray Absorption Fine Structure Technique (EXAFS). As the concentration of Sb is increased the disorder around Ce increases rapidly, and for x = 3, the peak for the nearest neighbor (Ce-Ge) is no longer observed. In contrast, for the Pt site, the disorder of the nearest neighbors is small even for x = 3. Thus the distortions are anisotropic and appear to be mainly in the plane of the Ce-Ge bonds and Ge4 rings. The increased disorder about Ce will decrease the lattice thermal conductivity at low temperatures, and likely is part of the reason for improved thermoelectric properties for the x = 1 sample.
    No preview · Article · Apr 2015 · IOP Conference Series Materials Science and Engineering
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    ABSTRACT: Experimental contributors to the field of Superconducting Materials share their informal views on the subject.
    Preview · Article · Apr 2015 · Physica C Superconductivity
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    ABSTRACT: Comprehensive investigations of superconductivity in the charge-doped high-temperature superconducting cuprates often involve examining the evolution of physical properties within a series of samples having controlled variations of some dopant element\char22{}most frequently oxygen. Many important observations have been extracted from such experiments, however, the associated measurements are by nature discrete snapshots of the evolving material. We demonstrate here a novel approach to sample preparation of the $\text{high-}{\mathit{\text{T}}}_{c}$ cuprate ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{x}$. By post-annealing a uniformly overdoped ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{x}(x$\approx${}7.0)$ film in a low pressure ${\text{O}}_{2}$ atmosphere with a thermal gradient across the film length, we have successfully grown a charge-gradient ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{$\nabla${}x}$ sample, i.e., a film having a varying oxygen doping level along the length of the substrate. Surprisingly, we observe three distinct regimes of oxygen distribution across the sample, as well as behavior pointing to a full alignment within the a-b plane.
    No preview · Article · Apr 2015 · Physical Review B

  • No preview · Article · Mar 2015 · Physical Review X
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    Y P Singh · D J Haney · I K Lum · B D White · M B Maple · M Dzero · C C Almasan
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    ABSTRACT: Charge transport measurements under magnetic field and pressure on Ce 1- x Yb x CoIn 5 single crystalline alloys revealed that: (i) relatively small Yb substitution suppresses the field induced quantum critical point, with a complete suppression for Yb doping x > 0.07; (ii) the superconducting transition temperature ( T c ) and Kondo lattice coherence temperature ( T coh ) decrease with x , yet they remain finite over the wide range of Yb concentrations; (iii) both T c and T coh increase with pressure; (iv) there are two contributions to resistivity, which show different temperature and pressure dependences, implying that both heavy and light quasiparticles contribute to inelastic scattering. We also analyzed the pressure dependence of both T coh and T c within the composite pairing theory. In the purely static limit, we find that the composite pairing mechanism necessarily causes opposite behaviors of T coh and T c with pressure: if Tcoh grows with pressure, T c must decrease with pressure and vice versa.
    Full-text · Article · Mar 2015 · Journal of Physics Conference Series
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    ABSTRACT: We report results of zero-field muon spin relaxation experiments on the filled-skutterudite superconductors~Pr$_{1-x}$Ce$_{x}$Pt$_4$Ge$_{12}$, $x = 0$, 0.07, 0.1, and 0.2, to investigate the effect of Ce doping on broken time-reversal symmetry (TRS) in the superconducting state. In these alloys broken TRS is signaled by the onset of a spontaneous static local magnetic field~$B_s$ below the superconducting transition temperature. We find that $B_s$ decreases linearly with $x$ and $\to 0$ at $x \approx 0.4$, close to the concentration above which superconductivity is no longer observed. The (Pr,Ce)Pt$_4$Ge$_{12}$ and isostructural (Pr,La)Os$_4$Sb$_{12}$ alloy series both exhibit superconductivity with broken TRS, and in both the decrease of $B_s$ is proportional to the decrease of Pr concentration. This suggests that Pr-Pr intersite interactions are responsible for the broken TRS\@. The two alloy series differ in that the La-doped alloys are superconducting for all La concentrations, suggesting that in (Pr,Ce)Pt$_4$Ge$_{12}$ pair-breaking by Ce doping suppresses superconductivity. For all $x$ the dynamic muon spin relaxation rate decreases somewhat in the superconducting state. This may be due to Korringa relaxation by conduction electrons, which is reduced by the opening of the superconducting energy gap.
    Preview · Article · Mar 2015
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    ABSTRACT: We report results of zero-field muon spin relaxation experiments on the filled-skutterudite superconductors ${\mathrm{Pr}}_{1$-${}x}{\mathrm{Ce}}_{x}{\mathrm{Pt}}_{4}{\mathrm{Ge}}_{12},x=0$, 0.07, 0.1, and 0.2, to investigate the effect of Ce doping on broken time-reversal symmetry (TRS) in the superconducting state. In these alloys broken TRS is signaled by the onset of a spontaneous static local magnetic field ${B}_{s}$ below the superconducting transition temperature. We find that ${B}_{s}$ decreases linearly with $x$ and $$\rightarrow${}0$ at $x$\approx${}0.4$, close to the concentration above which superconductivity is no longer observed. The ${\text{(Pr,Ce)Pt}}_{4}{\mathrm{Ge}}_{12}$ and isostructural ${\text{(Pr,La)Os}}_{4}{\mathrm{Sb}}_{12}$ alloy series both exhibit superconductivity with broken TRS, and in both the decrease of ${B}_{s}$ is proportional to the decrease of Pr concentration. This suggests that Pr-Pr intersite interactions are responsible for the broken TRS. The two alloy series differ in that the La-doped alloys are superconducting for all La concentrations, suggesting that in ${\text{(Pr,Ce)Pt}}_{4}{\mathrm{Ge}}_{12}$ pair-breaking by Ce doping suppresses superconductivity. For all $x$ the dynamic muon spin relaxation rate decreases somewhat in the superconducting state. This may be due to Korringa relaxation by conduction electrons, which is reduced by the opening of the superconducting energy gap.
    No preview · Article · Mar 2015 · Physical Review B
  • Y. Fang · D. Yazici · B. D. White · M. B. Maple

    No preview · Article · Mar 2015 · Physical Review B
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    B.D. White · J.D. Thompson · M.B. Maple
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    ABSTRACT: Over the past 35 years, research on unconventional superconductivity in heavy-fermion systems has evolved from the surprising observations of unprecedented superconducting properties in compounds that convention dictated should not superconduct at all to performing explorations of rich phase spaces in which the delicate interplay between competing ground states appears to support emergent superconducting states. In this article, we review the current understanding of superconductivity in heavy-fermion compounds and identify a set of characteristics that is common to their unconventional superconducting states. These core properties are compared with those of other classes of unconventional superconductors such as the cuprates and iron-based superconductors. We conclude by speculating on the prospects for future research in this field and how new advances might contribute towards resolving the long-standing mystery of how unconventional superconductivity works.
    Preview · Article · Feb 2015 · Physica C Superconductivity
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    ABSTRACT: La$_3$Co$_4$Sn$_{13}$ and La$_3$Ru$_4$Sn$_{13}$ were categorized as BCS superconductors. In a plot of the critical field $H_{c2}$ vs $T$, La$_3$Ru$_4$Sn$_{13}$ displays a second superconducting phase at the higher critical temperature $T_c^{\star}$, characteristic of inhomogeneous superconductors, while La$_3$Co$_4$Sn$_{13}$ shows bulk superconductivity below $T_c$. We observe a decrease in critical temperatures with external pressure and magnetic field for both compounds with $\frac{dT_c^{\star}}{dP} > \frac{dT_c}{dP}$. The pressure dependences of $T_c$ are interpreted according to the McMillan theory and understood to be a consequence of lattice stiffening. The investigation of the superconducting state of La$_3$Co$_x$Ru$_{4-x}$Sn$_{13}$ shows a $T_c^{\star}$ that is larger then $T_c$ for $x<4$. This unique and unexpected observation is discussed as a result of the local disorder and/or the effect of chemical pressure when Ru atoms are partially replaced by smaller Co atoms.
    Full-text · Article · Feb 2015

Publication Stats

15k Citations
1,393.97 Total Impact Points

Institutions

  • 1970-2015
    • University of California, San Diego
      • Department of Physics
      San Diego, California, United States
  • 2012
    • University of Alabama at Birmingham
      • Department of Physics
      Birmingham, Alabama, United States
  • 2001-2012
    • University of Silesia in Katowice
      • Institute of Physics
      Catowice, Silesian Voivodeship, Poland
  • 2010
    • General Atomics
      San Diego, California, United States
  • 1979-2008
    • Applied Physical Sciences
      Groton, Connecticut, United States
  • 1991-2007
    • University of San Diego
      • Department of Physics
      San Diego, California, United States
  • 2003
    • Max Planck Institute for Chemical Physics of Solids
      Dresden, Saxony, Germany
  • 2002-2003
    • Silesian University of Technology
      • Institute of Physics
      Gleiwitz, Silesian Voivodeship, Poland
  • 1975-2003
    • University of California, Berkeley
      • Department of Chemistry
      Berkeley, California, United States
  • 1996
    • University of California, Santa Barbara
      Santa Barbara, California, United States
  • 1987-1995
    • Los Alamos National Laboratory
      • • Materials Physics and Applications Division
      • • Nuclear Materials Science Group
      Лос-Аламос, California, United States
  • 1990
    • Iowa State University
      • Ames Laboratory
      Ames, Iowa, United States
    • The University of Texas at Austin
      • Department of Physics
      Texas City, TX, United States
  • 1982
    • University of Kentucky
      • Department of Physics & Astronomy
      Lexington, Kentucky, United States