science

Scanning Hall probe microscope

Scanning Hall probe microscope is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Scanning Hall probe microscope rather than just read about it. In short: Scanning Hall probe microscope (SHPM) is a variety of a scanning probe microscope which incorporates accurate sample approach and positioning of the scanning tunnelling microscope with a semiconductor Hall sensor. Developed in 1996 by Oral, Bending and Henini, SHPM allows mapping the magnetic induction associated with a sample.

Key takeaways

Scanning Hall probe microscope belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Scanning Hall probe microscope to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Scanning Hall probe microscope from memory before moving on to harder problems.

Reference excerpt

Scanning Hall probe microscope (SHPM) is a variety of a scanning probe microscope which incorporates accurate sample approach and positioning of the scanning tunnelling microscope with a semiconductor Hall sensor. Developed in 1996 by Oral, Bending and Henini, SHPM allows mapping the magnetic induction associated with a sample. Current state of the art SHPM systems utilize 2D electron gas materials (e.g. GaAs/AlGaAs) to provide high spatial resolution (~300 nm) imaging with high magnetic field sensitivity. Unlike the magnetic force microscope the SHPM provides direct quantitative information on the magnetic state of a material. The SHPM can also image magnetic induction under applied fields up to ~1 tesla and over a wide range of temperatures (millikelvins to 300 K). The SHPM can be used to image many types of magnetic structures such as thin films, permanent magnets, MEMS structures, current carrying traces on PCBs, permalloy disks, and recording media

Advantages to other magnetic raster scanning methods SHPM is a superior magnetic imaging technique due to many reasons. Although MFM provides higher spatial resolution (~30 nm) imaging, unlike the MFM technique, the Hall probe exerts negligible force on the underlying magnetic structure and is noninvasive. Unlike the magnetic decoration technique, the same area can be scanned over and over again. The magnetic field caused by hall probe is so minimal it has a negligible effect on sample it is measuring. The sample does not need to be an electrical conductor, unless using STM for height control. The measurement can be performed from 5 – 500 K in ultra high vacuum (UHV) and is nondestructive to the crystal lattice or structure. Tests requires no special surface preparation or coating. The detectable magnetic field sensitivity, is approximately 0.1 uT – 10 T. SHPM can be combined with other scanning methods such as STM.

Limitations There are some shortcomings or difficulties when working with an SHPM. High resolution scans become difficult due to the thermal noise of extremely small hall probes. There is a minimum scanning height distance due to the construction of the hall probe. (This is especially significant with 2DEG semi-conductor probes due to their multi-layer design). The scanning (lift) height affects obtained image. Scanning large areas takes a significant amount of time. There is a relatively short practical scanning range (order of 1000s micrometer) along any direction. The housing is important to shield electromagnetic noise (Faraday cage), acoustic noise (anti-vibrating tables), air flow (air isolation cupboard), and static charge on the sample (ionizing units).

References

Illustrations

Worked examples

Example 1 — a first encounter with Scanning Hall probe microscope

Start with the simplest possible case. Write down what Scanning Hall probe microscope claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Scanning Hall probe microscope before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Scanning Hall probe microscope ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Scanning Hall probe microscope

In research: Scanning Hall probe microscope appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Scanning Hall probe microscope in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Scanning Hall probe microscope is common in secondary-school and first-year university syllabi. It links to neighbouring topics Scanning probe microscopy, so understanding it makes those chapters shorter.
In everyday life: Look for Scanning Hall probe microscope outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Scanning Hall probe microscope in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Scanning Hall probe microscope means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Scanning Hall probe microscope out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Scanning Hall probe microscope in simple terms?

Why does Scanning Hall probe microscope matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Scanning Hall probe microscope?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Scanning Hall probe microscope.