Authors

H. M. Quddusi; C. M. Ramsey; J. C. Gonzalez-Pons; J. J. Henderson; E. del Barco; G. de Loubens;A. D. Kent

Comments

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Abbreviated Journal Title

Rev. Sci. Instrum.

Keywords

QUANTUM; RESONATORS; PHASE; Instruments & Instrumentation; Physics, Applied

Abstract

A sensor that integrates high-sensitivity micro-Hall effect magnetometry and high-frequency electron paramagnetic resonance spectroscopy capabilities on a single semiconductor chip is presented. The Hall-effect magnetometer (HEM) was fabricated from a two-dimensional electron gas GaAs/AlGaAs heterostructure in the form of a cross, with a 50x50 mu m(2) sensing area. A high-frequency microstrip resonator is coupled with two small gaps to a transmission line with a 50 Omega impedance. Different resonator lengths are used to obtain quasi-TEM fundamental resonant modes in the frequency range 10-30 GHz. The resonator is positioned on top of the active area of the HEM, where the magnetic field of the fundamental mode is largest, thus optimizing the conversion of microwave power into magnetic field at the sample position. The two gaps coupling the resonator and transmission lines are engineered differently-the gap to the microwave source is designed to optimize the loaded quality factor of the resonator (Q < = 150) while the gap for the transmitted signal is larger. This latter gap minimizes losses and prevents distortion of the resonance while enabling measurement of the transmitted signal. The large filling factor of the resonator permits sensitivities comparable to that of high-quality factor resonant cavities. The integrated sensor enables measurement of the magnetization response of micron scale samples upon application of microwave fields. In particular, the combined measurement of the magnetization change and the microwave power under cw microwave irradiation of single crystal of molecular magnets is used to determine of the energy relaxation time of the molecular spin states. In addition, real-time measurements of the magnetization dynamics upon application of fast microwave pulses are demonstrated.

Journal Title

Review of Scientific Instruments

Volume

79

Issue/Number

7

Publication Date

1-1-2008

Document Type

Article

Language

English

First Page

5

WOS Identifier

WOS:000258179400042

ISSN

0034-6748

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