Synthesis and characterization of Ca-doped LaMnAsO

Abstract

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.

Hole doping and antiferromagnetic correlations above the Néel temperature of the topological semimetal (Sr1−xKx)MnSb2

“…The peaks above T N are much broader with a FWHM that sets an upper limit to the 2D correlations at ∼ 80Å. Temperature dependence of the integrated intensity of the (010) peak as a function of temperature is shown in Figure 5 (b) over the extended temperature range (on a semi-logarithmic scale) indicating the persistence of magnetic scattering to the highest temperature measured with no indication of a transition up to ∼ 575 K. This 2D scattering has been observed before for other 2D systems, in particular for the the 1111 type AMnP nO systems with planes that are weakly coupled magnetically [12][13][14][15] .…”

“…SbMnSb layers in AMnSb 2 (referred to as Mn-112 compounds) are common to a large family of layered pnictides such as, AMn 2 P n 2 (referred to as Mn-122 compounds) and RMnP nO (R = La, Ce, Pr ...; 1111 compounds) that all settle into a G-or C-type AFM ground states corresponding to Nèel or checkerboard spin ordering within the square layer and either AFM or FM coupling between layers, respectively. [9][10][11][12][13][14][15] . It should be noted that the AFM is highly anisotropic as the inplane exchange coupling among nearest neighbors (NN) Mn 2+ moments in the MnP n planes (J 2D ) is much stronger than the weaker inter-plane coupling J i .…”

Hole Doping and Antiferromagnetic Correlations above the N{é}el temperature of the Topological Semimetal (Sr$_{1-x}$K$_x$)MnSb$_2$

“…The peaks above T N are much broader with a FWHM that sets an upper limit to the 2D correlations at ∼ 80 Å. Temperature dependence of the integrated intensity of the (010) peak as a function of temperature is shown in Figure 5 (b) over the extended temperature range (on a semi-logarithmic scale) indicating the persistence of magnetic scattering to the highest temperature measured with no indication of a transition up to ∼ 575 K. This 2D scattering has been observed before for other 2D systems, in particular for the the 1111 type AMnP nO systems with planes that are weakly coupled magnetically [12][13][14][15].…”

Crystal growth, microstructure, and physical properties of SrMnSb2

“…This kind of behavior is typical of AFM systems with in-plane exchange coupling among nearest neighbors (NN; J 2D ) that is much stronger than the inter-plane coupling J a , as has been observed in similar layered systems [30,31]. This behavior, is common to various compounds that posses MnSb layers such as AMnSb 2 and RMnP nO (R = La, Ce, Pr ...; P n = P, As, Sb compounds) that all settle into a Gor C-type AFM ground state [32][33][34][35][36][37][38]. However, at T ∼ 570 K a peak emerges that disappears above T ∼ 600 K. Upon cooling the same sample, the susceptibility displays a characteristic FM transition with a T C 580 K. This irreversible (2).…”