The existing magnetic recording read head technologies use one of the well-known magneto-resistance effects (i.e. anisotropic magneto-resistance, giant magneto-resistance or tunnelling magneto-resistance (TMR)) to read back the data from the magnetic recording medium. These are usually sophisticated devices that require a dc test current flowing through the sensor stack in order to measure its change in resistance (i.e. amplitude response signal) as a function of the fringing magnetic flux of the recorded bits, when the reader moves along the recorded track. In this paper, we propose the design of a new kind of highly sensitive read sensor for magnetic recording heads, which directly produces a voltage response without the need for a test current. This new design is based on the magneto-electric effect in laminated multiferroic materials. Such a magnetic read head is much simplified in terms of sensor construction (i.e. number of layers involved and horizontal biasing requirements) and has a range of potential advantages including similar sensitivity to that of the TMR heads, reduced power consumption, better thermal performances, excellent high frequency operation and reduced cost of production.
Composite multiferroics are an exciting class of engineered materials with a wide range of existing and potential applications. This paper describes an original finite element (FE) simulation for composite multiferroic devices. Detailed analysis is given on the flow of electric/magnetic fields between the composite regions with attention given to the conductivity of the magnetostrictive layers (piezoelectric assumed to be insulating). The simulation is verified against an existing FE code and against a theoretical analysis, also presented here. The issue of boundary and continuity conditions is discussed in detail and approximations made in both FE and analytical treatments are specified. We derive the I-V curves of the composite device when acting as a magnetic field detector, in both conducting and insulating cases. The magnetic field detector acts as a voltage source: we calculate its open-circuit voltage and internal impedance in each case.
Multiferroic (MF) materials are very promising candidates for new technologies and applications because they exhibit simultaneously multiple cooperative phenomena (i.e., magnetic, electric, and piezoeffects). The main feature of MF materials is the magnetoelectric (ME) effect, which can be used to engineer highly sensitive magnetic/electric sensors. In this paper, we discuss the requirements of a new kind of magnetic recording read head for 1Tbit∕in.2 recording densities, which is based on a MF structure. The MF sensor operates at room temperature via the strain mediated ME effect by producing a voltage signal in response to the magnetic field excitation from the recorded bits. We calculated the theoretical output from such a recording read head assuming a magnetic recording density of 1Tbit∕in.2. Our calculations demonstrate that the proposed read head technology could replace in the future the conventional magnetoresistive read heads bringing also a number of considerable advantages, as detailed in the paper.
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