# Nuclear magnetic resonance of 55Mn and 75As in MnAs

TL;DR: In this article, four sets of NMR signals, two each from 55Mn and 75As nuclei, have been observed, and the authors have shown that there is a phase transition at T 1 ≈ 220 K. This transition may be due to introduction of a local spontaneous distortion in the region of the domain walls in the lattice.

About: This article is published in Journal of Magnetism and Magnetic Materials.The article was published on 1982-11-01. It has received 15 citations till now. The article focuses on the topics: Hyperfine structure & Phase transition.

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TL;DR: In this paper, the authors discuss the compounds of transition elements with nonmetals and discuss the ferromagnetism of transition metal intermetallic compounds with non-metallic and semimetallic elements.

Abstract: Publisher Summary This chapter discusses the compounds of transition elements with nonmetals The ferromagnetism of transition metal intermetallic compounds are covered by Booth The compounds of transition metals with nonmetallic and semimetallic elements are described The scope of the combined physics and chemistry conference series International Conference of Solid Compounds of Transition Elements is reviewed However, sulfides are only treated when there is a direct connection to related selenides and tellurides The chapter discusses ferromagnetism, ferri-, antiferro-, and helimagnetism The compounds are listed according to the stoichiometric composition in the chapter The large groups TX and T 2 X, TT’X, where T is a transition element and X a nonmetal element is emphasized Various T m X n compounds are also described The compounds are arranged according to the nonmetallic elements of the third, fourth, fifth, and sixth group of the periodic table In the chemical formulas, the elements are arranged according to increasing atomic number The magnetic phase diagrams are presented according to the same rule The chapter also presents a survey of the relevant crystallographic structures

40 citations

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TL;DR: In this paper, the specific heat capacity of Mn 1+δ As 1−x Sb x single crystals with 0≦ x ≦1, 0 at. % ≦ δ ≦ 2 at.

14 citations

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TL;DR: The specific heat of magnetically ordered metallic CrxMn1−xAs crystals was determined in the temperature range 100 K < T < 500 K for nine compositions as mentioned in this paper, and several anomalies in the specific heat were observed and assigned to carrier localization effects, spin fluctuations, and long range spin ordering.

Abstract: The specific heat of magnetically ordered metallic CrxMn1−xAs crystals is determined in the temperature range 100 K < T < 500 K for nine compositions. Several anomalies in the specific heat are observed and assigned to carrier localization effects, spin fluctuations, and long range spin ordering. For the compositions x = 0.5, 0.4, 0.2, and 0.1 a sequence of two magnetic specific heat peaks are observed and interpreted in terms of a “magnetic alloy” model.
Die spezifische Warmekapazitat in Abhangigkeit von der Temperatur wird an neun Zusammensetzungen aus dem quasibinaren System CrxMn1−xAs bestimmt (100 K < T < 500 K). Verschiedene Anomalien werden beobachtet und mit Ladungstragerlokalisierung, Spinfluktuationen und magnetischer Fernordnung in Verbindung gebracht. Bei den Zusammensetzungen x = 0,1; 0,2; 0,4 und 0,5 werden zwei aufeinanderfolgende Maxima in der magnetischen spezifischen Warme entdeckt und innerhalb eines den binaren Legierungen analogen Modells gedeutet.

13 citations

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TL;DR: In this article, the magnetic structure and metal-insulator transition in antiferromagnetic (AFM) single crystals have been investigated by using nuclear magnetic resonance (NMR) measurements.

Abstract: The magnetic structure and metal-insulator transition in antiferromagnetic (AFM) BaMn${}_{2}$As${}_{2}$ and Ba${}_{1\ensuremath{-}x}$K${}_{x}$Mn${}_{2}$As${}_{2}$ single crystals have been investigated by ${}^{55}\phantom{\rule{0.16em}{0ex}}$Mn and ${}^{75}$As nuclear magnetic resonance (NMR) measurements. In the parent AFM insulator BaMn${}_{2}$As${}_{2}$ with a N\'eel temperature ${T}_{\mathrm{N}}=625$ K, we observed a ${}^{55}\phantom{\rule{0.16em}{0ex}}$Mn zero-field NMR (ZFNMR) spectrum and confirmed the G-type AFM structure from the field dependence of the ${}^{55}\phantom{\rule{0.16em}{0ex}}$Mn spectra and ${}^{75}$As NMR spectra below ${T}_{\mathrm{N}}$. In hole-doped crystals with $xg0.01$, similar ${}^{55}\phantom{\rule{0.16em}{0ex}}$Mn ZFNMR spectra were observed and the AFM state was revealed to be robust up to $x=0.4$ with the ordered moment nearly independent of $x$. The nuclear spin-lattice relaxation rates ($1/{T}_{1}$) for both nuclei in the doped samples follow the Korringa relation ${T}_{1}T=\text{const}$, indicating a metallic state. This confirms the coexistence of AFM ordered localized Mn spins and conduction carriers from a microscopic point of view. From the $x$ dependence of ${({T}_{1}T)}^{\ensuremath{-}1/2}$ for both nuclei, we conclude that this transition is caused by vanishing of the hole concentration as the transition is approached from the metallic side.

11 citations

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TL;DR: In this article, a supercell approach is applied to calculate the effective Hubbard U parameter for the Mn 3d electrons in bulk MnAs within both LSDA and generalized gradient approximations (GGA) to the exchange correlation functional without and with the Hubbard U correction.

10 citations

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TL;DR: In this paper, the excitation spectrum of an assembly of electronic spins in a Bloch wall structure is studied, assuming a uniaxial anisotropy, and the relaxation times are evaluated, taking into account the damping of the motion of the electronic spins and are compared with experimental values.

Abstract: The excitation spectrum of an assembly of electronic spins in a Bloch wall structure is studied, assuming a uniaxial anisotropy. The spectrum may be divided into two branches; one is a specific wall excitation and does not spread outside the wall, the other one is similar to the spin-wave excitation spectrum in a uniform ferromagnet. These calculations are used to study the properties of the nuclear magnetic resonances in a Bloch wall. The relaxation times are evaluated, taking into account the damping of the motion of the electronic spins and are compared with experimental values. The spin-spin coupling and the variation of the magnetization across the wall is also estimated.

201 citations

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01 Apr 1954

TL;DR: The lattice parameters of the isomorphous compounds MnAs, MnSb and MnBi have been measured over a temperature range which includes the temperatures at which certain magnetic transitions occur as discussed by the authors.

Abstract: The lattice parameters of the isomorphous compounds MnAs, MnSb and MnBi have been measured over a temperature range which includes the temperatures at which certain magnetic transitions occur. Characteristic changes develop near the magnetic transition temperatures and are of two kinds: (a) discontinuous changes of lattice dimensions (MnAs at 40°c, MnBi at 320°c), which are associated with magnetic transitions of the first order, (b) discontinuous changes of the temperature derivatives of the lattice parameters (MnAs at 130°c, MnSb at 320°c), associated with second-order magnetic transitions. Correlation of the results on MnAs and MnSb with those obtained by Greenwald on MnTe indicates that the magnetic exchange energy for manganese atoms at a distance r apart is a maximum for r = 2.94 °. The magnetic change which takes place in MnBi near 440°c is caused by decomposition of the material and is not a Curie point phenomenon.

132 citations

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TL;DR: The electronic state of high spin MnAs was investigated by using the polarized neutron technique as discussed by the authors, and the experimental results are summarized as follows: i) By analyzing the asphericity of the magnetic form factor with the free ion model, the numbers of electrons in the atomic levels are determined to be (1.0↑+0.3↓, 2.0↓) for (ψ x 0, ψ x ±, ψ u ± ) atomic levels, respectively.

Abstract: The electronic state of high spin MnAs was investigated by using the polarized neutron technique. The experimental results are summarized as follows: i) By analyzing the asphericity of the magnetic form factor with the free ion model, the numbers of electrons in the atomic levels are determined to be (1.0↑+0.3↓, 2.0↑, 0.7↑) for (ψ x 0 , ψ x ± , ψ u ± ) atomic levels, respectively. Therefore, Mn atoms are in the 3d 4 electronic state in MnAs. ii) This electron configuration is convenient to explain the observed metallic conductivity. iii) The spin density distribution shows the characteristics of the above mentioned electron configuration and the strong covalency with the anion As. iv) Spherical part of the magnetic form factor agrees with the calculated one for Mn + , not for Mn 3+ . But this does not imply the Mn atom is in the Mn + state.

52 citations

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22 citations