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We employ NMR techniques to investigate the nature of Mn spins in the I-II-V diluted magnetic semiconductor Li(Zn1−xMnx)P (x = 0.1, Curie temperature Tc = 25 K). We successfully identify the 7 Li NMR signals arising from the Li sites adjacent to Mn 2+ , and probe the static and dynamic properties of Mn spins. From the NMR spin-lattice relaxation data, we show that the Mn spin-spin interactions extend over many unit cells.

We report the discovery of a new diluted magnetic semiconductor, Li(Zn,Mn)P, in which charge and spin are introduced independently via lithium off-stoichiometry and the isovalent substitution of Mn 2+ for Zn 2+ , respectively. Isostructural to (Ga,Mn)As, Li(Zn,Mn)P was found to be a p-type ferromagnetic semiconductor with excess Lithium providing charge doping. First principles calculations indicate that excess Li is favored to partially occupy the Zn site, leading to hole doping. Ferromagnetism is mediated in semiconducting samples of relative low mobile carriers with a small coercive force, indicating an easy spin flip.

The origin of magnetism in metals has been traditionally discussed in two diametrically opposite limits: itinerant and local moments. Surprisingly, there are very few known examples of materials that are close to the itinerant limit, and their properties are not universally understood. In the case of the two such examples discovered several decades ago, the itinerant ferromagnets ZrZn2 and Sc3In, the understanding of their magnetic ground states draws on the existence of 3d electrons subject to strong spin fluctuations. Similarly, in Cr, an elemental itinerant antiferromagnet with a spin density wave ground state, its 3d electron character has been deemed crucial to it being magnetic. Here, we report evidence for an itinerant antiferromagnetic metal with no magnetic constituents: TiAu. Antiferromagnetic order occurs below a Néel temperature of 36 K, about an order of magnitude smaller than in Cr, rendering the spin fluctuations in TiAu more important at low temperatures. This itinerant antiferromagnet challenges the currently limited understanding of weak itinerant antiferromagnetism, while providing insights into the effects of spin fluctuations in itinerant–electron systems.

We present the results of muon spin relaxation/rotation, transmission electron microscopy, and neutron diffraction measurements performed on several specimens of BaTi 2 (As 1−x Sb x ) 2 O, which is known to have either charge density or spin density wave ordering at T DW for all x, and superconductivity below T c ≈ 1 K for x = 1. Zero-field muon spin relaxation measurements show no significant increase in relaxation rate at the density wave ordering temperature for any composition, indicating that the density wave is of the charge rather than spin type. The absence of any superstructure peaks in selected area electron and high-resolution neutron diffraction measurements below T DW suggests that the charge density wave does not involve modulation of atomic arrangement. Transverse field muon spin rotation measurements reveal a robust superconducting state below T c ≈ 1 K for x = 1. PACS number(s): 76.75.+i, 74.90.+n, 68.37.Og Layered oxypnictide systems, such as ATi 2 P n 2 O (A = Na 2 , Ba, (SrF) 2 , (SmO) 2 ; P n = As, Sb, Bi), have been found to possess interesting electronic and magnetic properties, including spin/charge density wave (S/CDW) ordering and superconductivity. 1-14 Although the superconducting phase transition in these systems occurs at low temperatures ( 5 K), 7-11 and in some cases not at all, they nevertheless share certain structural and electronic similarities with the cuprate and iron-pnictide compounds exhibiting hightemperature superconductivity. 15,16 These similarities include the presence of planar sheets of Ti 2 O square nets, in analogy to the CuO 2 sheets found in the cuprates, an electron configuration of 3d 1 that is electron-hole symmetric with the 3d 9 configuration of the cuprates, and the close proximity of the S/CDW instability to the superconducting state, as also observed in many cuprates and iron-pnictides. Given these similarities, these oxypnictide systems have the potential to yield important insights into high-temperature superconductivity.Resistivity and magnetic susceptibility measurements recently performed on isovalent systems for BaTi 2 P n 2 O, with P n = As 3− (T c = 0 K), Sb 3− (T c = 1.2 K), Bi 3− (T c = 4.6 K), have revealed an intriguing phase diagram with S/CDW ordering present for BaTi 2 (As 1−x Sb x ) 2 O, which is quickly suppressed and replaced by a superconducting state in BaTi 2 (Sb 1−y Bi y ) 2 O (Fig. 1). 10 Remarkably, the superconducting phase exhibits a two-dome structure as observed in iron pnictide, 17 suggesting the presence of multiple bands at the Fermi surface, in accordance with band calculations revealing contributions of d x 2 −y 2 , d z 2 , and d xy orbitals. 18-20 On the other hand, the hole-doped systems via aliovalent cation and anion substitution, (Ba 1−x Na x )Ti 2 Sb 2 O 8 and BaTi 2 (Sb 1−x Sn x ) 2 O, 11 respectively, display a different phase diagram with a robust S/CDW state even while supporting superconductivity with T c as high as 5.5 K in (Ba 0.67 Na 0.33 )Ti 2 Sb 2 O. In addition, any two-dome structure in the supercondu...