Magnetization reorientation in ${\text{Ga}}_{x}{\text{Mn}}_{1\ensuremath{-}x}\text{As}$ films: Planar Hall effect measurements

Magnetization reorientation in ${Ga}_{x} {Mn}_{1 - x} As$ films: Planar Hall effect measurements

Sunjae Chung, Sanghoon Lee, X. Liu, and J. K. Furdyna

Phys. Rev. B 81, 155209 – Published 19 April 2010

Abstract

The process of magnetization reorientation in a ferromagnetic semiconductor GaMnAs films was investigated using planar Hall effect measurements. In addition to the well-known two-step switching behavior that occurs during this process, we have observed two additional distinct features in field scan data of the planar Hall resistance (PHR). First, the region of the external field required to begin and complete the reorientation of magnetization from one easy axis to another strongly depends on the direction of the applied field. And second, the maximum amplitude of PHR is significantly reduced during magnetization reversal when the applied field is oriented near one of the easy axes of the GaMnAs film. We provide an explanation of these phenomena using the magnetic field dependence of the free-energy density and assuming the coexistence of multiple domains with three different directions of magnetization in the sample.

Received 26 November 2009

DOI:https://doi.org/10.1103/PhysRevB.81.155209

Authors & Affiliations

Sunjae Chung and Sanghoon Lee^*

Physics Department, Korea University, Seoul 136-701, Korea

X. Liu and J. K. Furdyna

Physics Department, University of Notre Dame, Notre Dame, Indiana 46556, USA

^*slee3@korea.ac.kr

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 81, Iss. 15 — 15 April 2010

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
Field scans of the PHR measured at 4 K for two GaMnAs films at several field directions $φ_{H}$ . The PHR data shown in left and right columns were obtained for the 3.1% and 6.2% samples, respectively. A clear difference in the transition rate for the first and the second reorientations of magnetization is seen in the PHR data of both samples. The conspicuous reduction in the PHR amplitude is also observed for fields near the easy axis of the film. The crystallographic directions and the angles for the external field and the magnetization used in the measurements shown in the inset.Reuse & Permissions
Figure 2
Evolution of magnetic free-energy density with increasing field in reverse direction for $φ_{H} = 20 °$ (left column) and $φ_{H} = 50 °$ (right column) for the 3.1% sample. The corresponding first and second transitions are schematically shown at the top of each column. The arrows on the minima indicate the directions of magnetization in the sample at the given field.Reuse & Permissions
Figure 3
Difference of free-energy density $Δ E_{f r e e} / M$ between two neighboring energy minima involved in the reorientation as a function of magnetic field for two field directions, $φ_{H} = 20 °$ (right column) and $φ_{H} = 50 °$ (left column) for the 3.1% and 6.2% samples. The solid and open symbols represent $Δ E_{f r e e} / M$ related to the first and the second reorientations, respectively. It is clear that the slopes of $Δ E_{f r e e} / M$ for the two reorientations are different, although both of them show a linear dependence on the field. The $E_{N} / M - E_{C} / M$ for crossing the $[1 \bar{1} 0]$ and [110] axes are shown as shaded regions.Reuse & Permissions
Figure 4
Angular dependence of $H_{N}$ and $H_{C}$ obtained from field scans of PHR for the 3.1% and 6.2% samples shown in Fig. 1. The circles and squares are used for reorientations of magnetization as it crosses the $[1 \bar{1} 0]$ and [110] axes, respectively. The solid and the open symbols represent $H_{N}$ and $H_{C}$ for each reorientation. Dashed lines are fitting curves from which the values of $E_{N} / M$ and $E_{C} / M$ were obtained using the methods demonstrated in Refs. 26, 28.Reuse & Permissions
Figure 5
Magnetic field dependence of $Δ E_{f r e e} / M$ for the condition when $R_{PHE}$ nearly vanishes in Fig. 1 ( $φ_{H} = 30 °$ for the 3.1% sample and $40 °$ , 6.2%). Unlike the cases for $φ_{H} = 20 °$ and $50 °$ shown in Fig. 3, the first and the second reorientations in both the upper (3.1% sample) and lower panel (6.2% sample) overlap in a certain field region, indicating a coexistence of multiple domains with three different directions. In the field region between 35 and 47 Oe for the 3.1% sample, and between 25 and 28 Oe for 6.2% sample, the reorientation occurs directly from the [100] to the $[\bar{1} 00]$ direction by a $180 °$ rotation.Reuse & Permissions

Physical Review B

covering condensed matter and materials physics

Magnetization reorientation in ${Ga}_{x} {Mn}_{1 - x} As$ films: Planar Hall effect measurements

Sunjae Chung, Sanghoon Lee, X. Liu, and J. K. Furdyna

Phys. Rev. B 81, 155209 – Published 19 April 2010

Abstract

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Access Options

Physical Review B

covering condensed matter and materials physics

Magnetization reorientation in GaxMn1−xAs films: Planar Hall effect measurements

Sunjae Chung, Sanghoon Lee, X. Liu, and J. K. Furdyna

Phys. Rev. B 81, 155209 – Published 19 April 2010

Abstract

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

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

Magnetization reorientation in ${Ga}_{x} {Mn}_{1 - x} As$ films: Planar Hall effect measurements