Antiferromagnetic ordering and dipolar interactions of ${\mathrm{YbAlO}}_{3}$

Antiferromagnetic ordering and dipolar interactions of ${YbAlO}_{3}$

L. S. Wu, S. E. Nikitin, M. Brando, L. Vasylechko, G. Ehlers, M. Frontzek, A. T. Savici, G. Sala, A. D. Christianson, M. D. Lumsden, and A. Podlesnyak

Phys. Rev. B 99, 195117 – Published 9 May 2019

Abstract

In this paper we report low-temperature magnetic properties of the rare-earth perovskite material ${YbAlO}_{3}$ . Results of elastic and inelastic neutron scattering experiment, magnetization measurements along with the crystalline electrical field (CEF) calculations, suggest that the ground state of Yb moments is a strongly anisotropic Kramers doublet, and the moments are confined in the $a b$ plane, pointing at an angle of $φ = \pm 23 . 5^{\circ}$ to the $a$ axis. With temperature decreasing below $T_{N} = 0.88$ K, Yb moments order into the coplanar but noncollinear antiferromagnetic (AFM) structure $A x G y$ , where the moments are pointed along their easy axes. In addition, we highlight the importance of the dipole-dipole interaction, which selects the type of magnetic ordering and may be crucial for understanding magnetic properties of other rare-earth orthorhombic perovskites. Further analysis of the broad diffuse neutron scattering shows that one-dimensional interaction along the $c$ axis is dominant and suggests ${YbAlO}_{3}$ as a new member of one-dimensional quantum magnets.

Received 28 February 2019

DOI:https://doi.org/10.1103/PhysRevB.99.195117

Physics Subject Headings (PhySH)

Magnetic interactions

Antiferromagnets

Inelastic neutron scattering Magnetization measurements Specific heat measurements

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

L. S. Wu^1,2, S. E. Nikitin^3,4, M. Brando³, L. Vasylechko⁵, G. Ehlers⁶, M. Frontzek¹, A. T. Savici¹, G. Sala¹, A. D. Christianson^7,1, M. D. Lumsden¹, and A. Podlesnyak^1,*

¹Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
²Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
³Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany
⁴Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01069 Dresden, Germany
⁵Lviv Polytechnic National University, 79013 Lviv, Ukraine
⁶Neutron Technologies Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
⁷Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA

^*Corresponding author: podlesnyakaa@ornl.gov

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 99, Iss. 19 — 15 May 2019

Reuse & Permissions

Access Options

Article Available via CHORUS

Download Accepted Manuscript

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
(a) Crystal structure of ${YbAlO}_{3}$ , where Yb atoms are surrounded by eight nearby distorted Al-O octahedra. (b) Local chemical environment of ${Yb}^{3 +}$ located at $z = c / 4$ , considering twelve nearest Oxygen neighbors: four O1 (green circles) sites in the same $z = c / 4$ plane, four O2 (red circles) sites above and below the $z = c / 4$ plane. The red vector indicates the magnetic moment of ${Yb}^{3 +}$ , which lies in the $a b$ -plane, with a tilting angle from the $a$ -axis. (c) Contour plot of the inelastic neutron scattering spectrum of ${YbAlO}_{3}$ measured at 10 K. A flat CEF mode is observed, indicated by the red dashed line. (d) Energy dependent intensity integrated over the wave vector range $| Q | = [3, 7] Å^{- 1}$ . A Gaussian function (blue line) is fit to the data, with a linear background (red dash line) subtracted. Inset: Sketch of the four isolated CEF doublet states of ${Yb}^{3 +}$ , where the eight fold degeneracy of $J = 7 / 2$ ( $2 J + 1 = 8$ ) is lifted to four doublet states $E_{0}, E_{1}, E_{2}, E_{3}$ , due to the low point symmetry. The first excited levels are well separated from the ground doublet by $29.7 \pm 0.07$ meV, which is about 345 K.
Reuse & Permissions
Figure 2
(a) Field dependent magnetization $M$ of ${YbAlO}_{3}$ , measured at 2 K, with the field along different principal axes. The solid lines are the calculated Brillouin functions, as explained in the text. (b) Angle-dependent magnetization measured at $T = 2$ K and $B = 5$ T. The red line represents the fit, as explained in the text. Inset: Schematic view of the Yb magnetic moment configuration in the ordered state, where $φ$ is the angle between the Ising moments and the $a$ axis, and the angle $θ$ indicates the direction of the applied field in the $a b$ plane. (c),(d) Contour plot of the measured magnetization $M$ and magnetic susceptibility $d M / d B$ at 2 K, with magnetic field rotating in the $a b$ plane. The red and blue dashed lines indicate the angle dependent critical fields.
Reuse & Permissions
Figure 3
(a) Configurations of the four symmetry allowed magnetic structures. The red vectors indicate the Yb magnetic moment directions, which are tilted by angle $φ$ from the $a$ axis. (b) Calculated field dependence of the dipole-dipole energy for each of the four magnetic structures. For magnetic field applied along the $a$ and $b$ axes, the ferromagnetic $F x C y$ and $C x F y$ configurations will be the new ground states, with critical fields of 0.3 T and 1.0 T, respectively. (c) Calculated angle dependence of the dipole-dipole energy for the two antiferromagnetic structures, $G x A y$ and $A x G y$ . With $φ = 23 . 5^{\circ}$ , the configuration $A x G y$ is selected as the ground state for ${YbAlO}_{3}$ , as indicated by the red dashed line.
Reuse & Permissions
Figure 4
(a) Sketch of the magnetic dipole-dipole interaction between two Ising magnetic moments ${\vec{m}}_{1}$ and ${\vec{m}}_{2}$ . The two moments are separated by distance ${\vec{r}}_{12}$ and make an angle $\pm φ$ with the $a$ axis. The angle $α = 47 . 73^{\circ}$ is the angle between vector ${\vec{r}}_{12}$ and the crystal $a$ axis. (b) Contour plot of the calculated dipole-dipole interaction as a function of both angles $α$ and $φ$ . The white dashed line indicates the line of ‘magic’ angles, where the dipolar interaction vanishes between the two nearby Ising moments. The stars indicate that the rare-earth orthorhombic perovskites of interest here are all located in the vicinity of these ‘magic’ angles, with very weak dipolar interaction in the $a b$ plane.
Reuse & Permissions
Figure 5
(a) Magnetization $M$ (black) and temperature derivative $d M / d T$ (red) of ${YbAlO}_{3}$ , with applied field $B = 0.1$ T along the $a$ axis. The blue dashed line indicates the antiferromagnetic transition at $T_{N} = 0.85$ K. (b)–(d) Contour plot of the magnetic scattering of ${YbAlO}_{3}$ in the $(0 K L)$ plane, integrated over wave vector $H = [- 0.2, 0.2]$ r. l. u., and energy $E = [- 0.1, 0.1]$ meV, at different temperatures, 50 mK (b), 1.0 K (c), and 2.0 K (d), respectively.
Reuse & Permissions
Figure 6
(a) Constant energy cut along wave vector $K$ , integrated over $E = [- 0.1, 0.1]$ meV, $H = [- 0.2, 0.2]$ r. l. u., and $L = [0.9, 1.1]$ r. l. u. (b) Constant energy cut along wave vector $L$ , integrated over $E = [- 0.1, 0.1]$ meV, $H = [- 0.2, 0.2]$ , and $K = [- 0.2, 0.2]$ r. l. u. The instrumental resolution (gray bar) is estimated from the full width at half maximum (FWHM) of the magnetic (001) peak measured at 50 mK. The solid lines are the fit with Lorentzian functions, as explained in the text. (d) The temperature dependent correlation length along different directions. The red dashed line indicates the magnetic transition at 0.88 K.
Reuse & Permissions

Physical Review B

covering condensed matter and materials physics

Antiferromagnetic ordering and dipolar interactions of ${YbAlO}_{3}$

L. S. Wu, S. E. Nikitin, M. Brando, L. Vasylechko, G. Ehlers, M. Frontzek, A. T. Savici, G. Sala, A. D. Christianson, M. D. Lumsden, and A. Podlesnyak

Phys. Rev. B 99, 195117 – Published 9 May 2019

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Access Options

Physical Review B

covering condensed matter and materials physics

Antiferromagnetic ordering and dipolar interactions of YbAlO3

L. S. Wu, S. E. Nikitin, M. Brando, L. Vasylechko, G. Ehlers, M. Frontzek, A. T. Savici, G. Sala, A. D. Christianson, M. D. Lumsden, and A. Podlesnyak

Phys. Rev. B 99, 195117 – Published 9 May 2019

Abstract

Physics Subject Headings (PhySH)

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Access Options

Authorization Required

Other Options

Download & Share

Images

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

Antiferromagnetic ordering and dipolar interactions of ${YbAlO}_{3}$