Y. J. Uemura

Li(Zn,Mn)As as a new generation ferromagnet based on a I–II–V semiconductor

In a prototypical ferromagnet (Ga,Mn)As based on a III-V semiconductor, substitution of divalent Mn atoms into trivalent Ga sites leads to severely limited chemical solubility and metastable specimens available only as thin films. The doping of hole carriers via (Ga,Mn) substitution also prohibits electron doping. To overcome these difficulties, Masek et al. theoretically proposed systems based on a I-II-V semiconductor LiZnAs, where isovalent (Zn,Mn) substitution is decoupled from carrier doping with excess/deficient Li concentrations. Here we show successful synthesis of Li(1+y)(Zn(1-x)Mn(x))As in bulk materials. Ferromagnetism with a critical temperature of up to 50 K is observed in nominally Li-excess (y=0.05-0.2) compounds with Mn concentrations of x=0.02-0.15, which have p-type metallic carriers. This is presumably due to excess Li in substitutional Zn sites. Semiconducting LiZnAs, ferromagnetic Li(Zn,Mn)As, antiferromagnetic LiMnAs, and superconducting LiFeAs systems share square lattice As layers, which may enable development of novel junction devices in the future.

Bose-Einstein to BCS crossover picture for high-Tc cuprates

Abstract Combining (1) the universal correlations between Tc and n s /m ∗ (superconducting carrier density/effective mass) and (2) the pseudo-gap behavior in the underdoped region, we obtain a picture to describe superconductivity in cuprate systems in evolution from Bose-Einstein to BCS condensation. Overdoped and Zn-substituted cuprate systems show signatures of reduced superfluid density in a microscopic phase separation. Scaling of Tc to the superfluid volume density ns in all these cases indicate importance of Bose condensation.Combining (1) the universal correlations between

Superconducting state coexisting with a phase-separated static magnetic order in (Ba,K)Fe2As2, (Sr,Na)Fe2As2, and CaFe2As2

T_{c}

Reduction of Ordered Moment and Néel Temperature of Quasi-One-Dimensional Antiferromagnets Sr2CuO3 and Ca2CuO3

and

Static magnetic order in La1.875Ba0.125CuO4

n_{s}/m^{*}

Searching for spontaneous magnetic order in an organic ferromagnet. μSR studies of β-phase p-NPNN

(superconducting carrier density / effective mass) and (2) the pseudo-gap behavior in the underdoped region, we obtain a picture to describe superconductivity in cuprate systems in evolution from Bose-Einstein to BCS condensation. Overdoped and Zn-substituted cuprate systems show signatures of reduced superfluid density in a microscopic phase separation. Scaling of

A new way of determining concentrations in P.I.X.E. trace element analysis

T_{c}

Muon-spin-relaxation studies of magnetic order and superfluid density in antiferromagnetic NdFeAsO, BaFe2As2, and superconducting Ba1-xKxFe2As2

to the superfluid volume density

Muon spin relaxation investigation of the spin dynamics of geometrically frustrated antiferromagnets Y2Mo2O7 and Tb2Mo2O7.

n_{s}

Muon spin resonance by strong pulsed r.f. field with pulsed muons

in all these cases indicate importance of Bose condensation.