The ultimate speed of magnetic switching in granular recording media
The ultimate speed of magnetic switching in granular recording media
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DOI：
10.1038/nature02438
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发表时间：
2004-04
期刊：
影响因子：
64.8
通讯作者：
I. Tudosa;C. Stamm;A. Kashuba;F. King;H. Siegmann;J. Stöhr;G. Ju;B. Lu;D. Weller
中科院分区：
文献类型：
--
作者：
I. Tudosa;C. Stamm;A. Kashuba;F. King;H. Siegmann;J. Stöhr;G. Ju;B. Lu;D. Weller
在磁存储器设备中，通过选择性地将各个磁畴的磁化矢量设置为“向上”或“向下”来记录逻辑位。在这种器件中，最快和最有效的记录方法涉及进动切换：当磁场Bp作为写入脉冲在周期τ上施加时，磁化矢量围绕磁场进动，直到Bp τ达到切换发生的阈值。因此，增加写入脉冲Bp的幅度可以大大缩短所需的切换时间τ，并允许更快的磁记录。在这里，我们使用非常短的脉冲，一个非常高的磁场表明，在这些极端条件下，进动切换在磁介质中支持高比特密度不再发生在定义明确的磁场强度;相反，切换随机发生在很宽的磁场范围内。我们将这种行为归因于短场和高场脉冲负载下自旋铁磁序的瞬时崩溃，从而建立了确定性开关和磁记录速度的最终极限。
In magnetic memory devices, logical bits are recorded by selectively setting the magnetization vector of individual magnetic domains either ‘up’ or ‘down’. In such devices, the fastest and most efficient recording method involves precessional switching,,,: when a magnetic fieldBpis applied as a write pulse over a periodτ, the magnetization vector precesses about the field untilBpτreaches the threshold value at which switching occurs. Increasing the amplitude of the write pulseBpmight therefore substantially shorten the required switching timeτand allow for faster magnetic recording. Here we use very short pulses of a very high magnetic field to show that under these extreme conditions, precessional switching in magnetic media supporting high bit densities no longer takes place at well-defined field strengths; instead, switching occurs randomly within a wide range of magnetic fields. We attribute this behaviour to a momentary collapse of the ferromagnetic order of the spins under the load of the short and high-field pulse, thus establishing an ultimate limit to the speed of deterministic switching and magnetic recording.