Persistence of local-moment antiferromagnetic order in Ba<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:math>K<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mi>x</mml:mi></mml:msub></mml:math>Mn<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:ms

Lamsal, Jagat; Tucker, G. S.; Heitmann, Thomas; Kreyßig, A.; Jesche, Anton; Pandey, Abhishek; Wang, Tian; McQueeney, R. J.; Johnston, D. C.; Goldman, A. I.

doi:10.1103/physrevb.87.144418

Cited by 41 publications

(73 citation statements)

References 19 publications

(15 reference statements)

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“…It has been shown that T N in the MnAs layer of Mn-122 compounds is robust against substitution of the layers adjacent to it. Indeed, substituting K for Ba in Ba 1−x K x Mn 2 As 2 shows that T N of the MnAs layers changes negligibly in the range 0 x 0.2 [19,20]. Figure 8 shows the linewidths of the (100) and (101) as a function of temperature that are extracted from fitting the diffraction patterns in scans similar to those in Fig.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of Ca-doped LaMnAsO

Liu

Straszheim

Das

et al. 2018

Phys. Rev. Materials

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We report on our attempt to hole-dope the antiferromagnetic semiconductor LaMnAsO by substitution of the La3+ site by Ca2+. We use neutron and x-ray diffraction, magnetic susceptibility, and transport techniques to characterize polycrystalline (La1−xCax)MnAsO samples prepared by solid-state reaction and find that the parent compound is highly resistant to substitution with an upper limit x≤0.01. Magnetic susceptibility of the parent and the x=0.002(xnom=0.04) compounds indicate a negligible presence of magnetic impurities (i.e., MnO or MnAs). Rietveld analysis of neutron and x-ray diffraction data shows the preservation of both the tetragonal (P4/nmm) structure upon doping and the antiferromagnetic ordering temperature, TN=355±5 K. We report on our attempt to hole-dope the antiferromagnetic semiconductor LaMnAsO by substitution of the La 3+ site by Ca 2+ . We use neutron and x-ray diffraction, magnetic susceptibility, and transport techniques to characterize polycrystalline (La 1−x Ca x )MnAsO samples prepared by solid-state reaction and find that the parent compound is highly resistant to substitution with an upper limit x 0.01. Magnetic susceptibility of the parent and the x = 0.002 (x nom = 0.04) compounds indicate a negligible presence of magnetic impurities (i.e., MnO or MnAs). Rietveld analysis of neutron and x-ray diffraction data shows the preservation of both the tetragonal (P 4/nmm) structure upon doping and the antiferromagnetic ordering temperature, T N = 355 ± 5 K.

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Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of Ca-doped LaMnAsO

Liu

Straszheim

Das

et al. 2018

Phys. Rev. Materials

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“…Since large sized single crystals can be grown by self-flux method in many of these cases , doped BaFe 2 As 2 materials provide a unique opportunity to study the evo-lution of the static AF order and spin excitations as a function of hole, electron, and isovalent doping throughout the entire AF order to superconductivity phase diagram, and determine their connection with superconductivity. These experiments, together with neutron scattering studies of related materials (Inosov et al, 2013;Ishikado et al, 2009;Johnston et al, 2011;Lamsal et al, 2013;Marty et al, 2011;Shamoto et al, 2010;Simonson et al, 2012;Taylor et al, 2013;Wakimoto et al, 2010), will establish the common features in the magnetic order and spin excitations in different families of iron-based superconductors. The outcome, together with the results from high-T c copper oxide and heavy fermion superconductors, and can form a basis to determine if magnetism is indeed responsible for superconductivity in these materials (Scalapino, 2012).…”

Section: Introductionmentioning

confidence: 99%

Antiferromagnetic order and spin dynamics in iron-based superconductors

2015

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High-transition temperature (high-Tc) superconductivity in the iron pnictides/chalcogenides emerges from the suppression of the static antiferromagnetic order in their parent compounds, similar to copper oxides superconductors. This raises a fundamental question concerning the role of magnetism in the superconductivity of these materials. Neutron scattering, a powerful probe to study the magnetic order and spin dynamics, plays an essential role in determining the relationship between magnetism and superconductivity in high-Tc superconductors. The rapid development of modern neutron time-of-flight spectrometers allows a direct determination of the spin dynamical properties of iron-based superconductors throughout the entire Brillouin zone. In this review, we present an overview of the neutron scattering results on iron-based superconductors, focusing on the evolution of spin excitation spectra as a function of electron/hole-doping and isoelectronic substitution. We compare spin dynamical properties of iron-based superconductors with those of copper oxide and heavy fermion superconductors, and discuss the common features of spin excitations in these three families of unconventional superconductors and their relationship with superconductivity.

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“…Unlike the cuprates, the moments on Mn are large (S ≈ 2 to 5/2). In conjunction with large magnetic interactions (with a Néel transition temperature of T N = 625 K) [11,14,15], both neutron diffraction [16] and 75 As nuclear magnetic resonance [17] find that long-range AFM ordering is robust with hole doping, even at K concentrations up to 40%.Measurements and calculations of the electronic band structure of BaMn 2 As 2 indicate that significant hybridization exists between Mn and As orbitals [18][19][20]. Thus, we expect there to be a strong effect of hole doping on magnetic exchange interactions, Mn moment size and AFM order.…”

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Robust antiferromagnetic spin waves across the metal-insulator transition in hole-doped BaMn2As2

et al. 2017

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BaMn2As2 is an antiferromagnetic insulator where a metal-insulator transition occurs with hole doping via the substitution of Ba with K. The metal-insulator transition causes only a small suppression of the Néel temperature (TN) and the ordered moment, suggesting that doped holes interact weakly with the Mn spin system. Powder inelastic neutron scattering measurements were performed on three different powder samples of Ba1−xKxMn2As2 with x =0, 0.125 and 0.25 to study the effect of hole doping and metallization on the spin dynamics of these compounds. We compare the neutron intensities to a linear spin wave theory approximation to the J1 − J2 − Jc Heisenberg model. Hole doping is found to introduce only minor modifications to the exchange energies and spin gap. The changes observed in the exchange constants are consistent with the small drop of TN with doping. INTRODUCTIONThe parent compounds of unconventional superconductors are typically antiferromagnetic (AFM), although they may be initially metals (as in the iron pnictides [1]) or Mott insulators (as in the copper oxide superconductors [2]). In either case, chemical substitution is often employed to destabilize the AFM ordered state and give rise to a superconducting ground state over some composition range. For the iron arsenides, they are already metallic and adding charge carriers serves to modify the Fermi surface and destabilize nesting-driven spin-density wave AFM order, resulting in superconductivity. In BaFe 2 As 2 , electrons or holes can be added via chemical substitutions such as Ba(Fe 1−x M x ) 2 As 2 with M = Co or Ni [3][4][5][6][7][8][9] and Ba 1−x K x Fe 2 As 2 [10], respectively.On the other hand, the effect of chemical substitutions in the copper oxides, such as La 2 CuO 4 , are twofold. Since they are insulators, chemical substitutions (such as La 2−x Sr x CuO 4 ) must both metallize the system and disrupt long-range AFM order in order to make the conditions favorable for superconductivity. In other words, both a metal-insulator transition and suppression of AFM order are necessary for superconductivity to appear in the cuprates.In attempting to find some commonality between the arsenides and cuprates, we search for other compounds that bridge these two systems. One possible system is BaMn 2 As 2 which shares the same crystal structure as BaFe 2 As 2 . Similar to cuprates, BaMn 2 As 2 is a quasitwo-dimensional AFM insulator possessing a square lattice of magnetic moments that order into a G-type AFM (checkerboard) pattern [11]. Also similar to the cuprates, a metal-insulator transition can be induced in BaMn 2 As 2 by replacing small amounts (a few percent) of Ba with K which effectively adds hole carriers [12,13]. Unlike the cuprates, the moments on Mn are large (S ≈ 2 to 5/2). In conjunction with large magnetic interactions (with a Néel transition temperature of T N = 625 K) [11,14,15], both neutron diffraction [16] and 75 As nuclear magnetic resonance [17] find that long-range AFM ordering is robust with hole doping, even at K concentra...

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Persistence of local-moment antiferromagnetic order in Ba1−xKxMn2

Cited by 41 publications

References 19 publications

Synthesis and characterization of Ca-doped LaMnAsO

Synthesis and characterization of Ca-doped LaMnAsO

Antiferromagnetic order and spin dynamics in iron-based superconductors

Robust antiferromagnetic spin waves across the metal-insulator transition in hole-doped BaMn2As2

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