Macroeconomic Regimes

We estimate a New-Keynesian macro model accommodating regime-switching behavior in monetary policy and in macro shocks. Key to our estimation strategy is the use of survey-based expectations for inflation and output. Output and inflation shocks shift to the low volatility regime around 1985 and 1990, respectively. However, we also identify multiple shifts between accommodating and active monetary policy regimes, which play an as important role as shock volatility in driving the volatility of the macro variables. We provide new estimates of the onset and demise of the Great Moderation and quantify the relative role played by macro-shocks and monetary policy. The estimated rational expectations model exhibits indeterminacy in the mean square stability sense, mainly because monetary policy is excessively passive

Macroeconomic Regimes

We estimate a New-Keynesian macro model accommodating regime-switching behavior in monetary policy and in macro shocks. Key to our estimation strategy is the use of survey-based expectations for inflation and output. Output and inflation shocks shift to the low volatility regime around 1985 and 1990, respectively. However, we also identify multiple shifts between accommodating and active monetary policy regimes, which play an as important role as shock volatility in driving the volatility of the macro variables. We provide new estimates of the onset and demise of the Great Moderation and quantify the relative role played by macro-shocks and monetary policy. The estimated rational expectations model exhibits indeterminacy in the mean square stability sense, mainly because monetary policy is excessively passive

Magnetic anisotropy of crystalline Fe films grown on (001) GaAs substrates using Ge buffer layers

Magnetic anisotropy of Fe films grown on (001) GaAs substrates using Ge buffer layers were investigated by planar Hall effect measurements. In addition to phenomena arising from dominant cubic symmetry of the Fe specimen, the study of angular dependence of magnetization reversal revealed breaking of this symmetry in the form of systematic asymmetric shifts of magnetic hysteresis loops around the <110 > crystallographic directions. We ascribe such symmetry breaking to an admixture of uniaxial anisotropy associated with the [100] direction in the Fe film. To determine the parameters associated with this uniaxial anisotropy, we quantitatively analyze the asymmetric shifts of the hysteresis loop centers from the <110 > directions. Even though the value of these parameters turns out to be relatively small compared to that of the cubic anisotropy (by about two orders of magnitude), they survive up to room temperature

Magnetization reversal in trilayer structures consisting of GaMnAs layers with opposite signs of anisotropic magnetoresistance

Abstract Magnetization reversal in a GaMnAs trilayer system consisting of two GaMnAs layers separated by a Be-doped GaAs spacer was investigated by magnetotransport measurements. The rotation of magnetization in the two GaMnAs layers is observed as two abrupt independent transitions in planar Hall resistance (PHR). Interestingly, one GaMnAs layer manifests a positive change in PHR, while the other layer shows a negative change for the same rotation of magnetization. Such opposite behavior of the two layers indicates that anisotropic magnetoresistance (AMR) has opposite signs in the two GaMnAs layers. Owing to this opposite behavior of AMR, we are able to identify the sequence of magnetic alignments in the two GaMnAs layers during magnetization reversal. The PHR signal can then be decomposed into two independent contributions, which reveal that the magnetic anisotropy of the GaMnAs layer with negative AMR is predominantly cubic, while it is predominantly uniaxial in the layer with positive AMR. This investigation suggests the ability of engineering the sign of AMR in GaMnAs multilayers, thus making it possible to obtain structures with multi-valued PHR, that can be used as multinary magnetic memory devices