Define Curie Temperature
Curie point is also named as Curie Temperature. Curie temperature is the temperature above which some changes are made due to its impact on certain magnetic materials. Curie temperature diminishes the magnetic properties of the material.
If you consider some rocks and minerals, then you will notice that there is remnant magnetism. Also, the remnant magnetism appears below the Curie point.
The temperature is about 570 °C (almost 1,060 °F). This is the result of the general magnetic mineral magnetite. ‘Pierre Curie’ – is the name behind the temperature of Curie point. Find the definition of curie point in brief.
Do you know the curie point of nickel?
Nickel Curie point possesses a temperature of 627 K.
Curie Temperature Definition
Curie point definition is very easy to understand. It is named after the French physicist. He had discovered it in 1895. He also put forward certain laws that were related to some magnetic properties in temperature change.
Let’s find something interesting that is related to the Curie point. Consider an example of iron—atoms with a temperature of 770 °C (1,418 °F). Each iron atom acts as a tiny magnet at this temperature spontaneously. Each of them will align themselves as some kind of magnetic material.
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In the case of pure iron, the atomic magnets are distributed within each microscopic region. Pure iron is considered among the categories of Ferromagnetic materials. The directions of the magnetic fields are the same so that their magnetic fields strengthen each other.
Well, you won’t find the same in antiferromagnetic materials. Their materials possess the atomic magnets that have the alternate property of magnetic fields. They act in opposite directions. This tendency explains that their magnetic fields cancel each other.
You may notice different types of spontaneous arrangements in ferrimagnetic materials. This is a mixture of both patterns. They are generally involved in two types of magnetic atoms. This feature enables them to yield the property of partial reinforcement of magnetic fields.
Miscellaneous Facts on Currie Point
Three classes are there that involve the raising of temperature to the Curie point. They apply to any type of material. Numerous spontaneous arrangements are found in these types of disrupts.
Among them, only a few weak magnetic behaviours exist. All of these processes are kind of more general. We call them paramagnetism. For information, you should know about the highest Curie point as the value for cobalt is 1,121 °C (2,050 °F).
The rise of temperature above the Curie point can lead to the production of roughly similar patterns of decreasing paramagnetism. This behavior is constant in all three classes of materials.
When you try to cool down the temperature of these materials below their Curie points, the magnetic atoms will start to realign spontaneously. This is the behaviour that initiates the effect of ferromagnetism or antiferromagnetism among the metals.
Néel temperature is the behavior that is pointing towards the antiferromagnetic Curie point. The name is given to the term in honour of the French physicist Louis Néel. He had explained antiferromagnetism successfully in 1936.
Application of Curie Point
Steel wire has atoms that tend to behave as a magnet when they are subjected to the electric field. At this moment, they act like tiny magnets. Each end of the steel rod turns into a north and south pole.
Generally, these atoms do not possess any significant direction of the magnetic field. They all are in different directions. So, you can say that the steel does not exhibit any type of net magnetic field.
At a moment when you try to bring a magnet close to the wire, it makes the steel atoms close to each other and stays in a lineup format. The queued atomic magnets help the steel wire to convert into a magnet. The steel does not have any magnetic behavior in nature, but it turns into something that attracts the original magnet.
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The process of magnetization can be disturbed by high temperatures. Thermal energy is very much responsible for the steel atoms to wobble back and forth. The energy leads to the disturbing tendency of the magnetic alignment.
When you notice the maximum vibration among the atoms, the behaviour of being the atomic magnets do not remain as usual. At this moment, the steel gives up its magnetism. Curie point is the reason for which this occurs.
Do You Know?
You must have heard of a core of molten iron inside the earth. This iron ore cannot be magnetized, which has a temperature above the Curie point.
How the earth behaves as a magnet and possesses a magnetic field. Due to its magnetism, it has a North and a South magnetic pole. An electromagnet is a reason for the generation of the magnetic field of the earth.
Do you know why? This is due to the passage of electrical currents flowing through the liquid metal core deep inside the earth.
FAQs on Curie Point
1. What is the Curie point or Curie temperature in Physics?
The Curie point, also known as the Curie temperature (T_c), is the specific temperature at which a ferromagnetic or ferrimagnetic material undergoes a phase transition and becomes paramagnetic. Below this temperature, the material exhibits strong magnetic properties, but above it, thermal energy becomes strong enough to disrupt the long-range ordering of magnetic moments, causing the material to lose its permanent magnetism.
2. What are the Curie temperatures for common ferromagnetic materials like iron, cobalt, and nickel?
The Curie temperature is a unique property for each material. For the most common ferromagnetic elements, the approximate Curie points are:
- Iron (Fe): 770 °C (1043 K)
- Cobalt (Co): 1121 °C (1394 K)
- Nickel (Ni): 354 °C (627 K)
3. What happens to a ferromagnetic material at a microscopic level when it is heated above its Curie point?
At a microscopic level, a ferromagnetic material is composed of small regions called magnetic domains, where the magnetic moments of atoms are aligned. When the material is heated, the thermal energy causes atoms to vibrate more intensely. At the Curie temperature, this thermal agitation becomes powerful enough to overcome the exchange interaction that holds the atomic magnets in alignment. As a result, the magnetic domains are disrupted, the magnetic moments become randomly oriented, and the material's net magnetism drops to zero, transitioning it into a paramagnetic state.
4. How does Curie's Law relate to the behaviour of materials above the Curie temperature?
Above the Curie temperature, a material behaves as a paramagnet. Curie's Law describes this behaviour, stating that the magnetic susceptibility (χ) of a paramagnetic material is inversely proportional to the absolute temperature (T). The formula is often written as χ = C / (T - T_c), which is the Curie-Weiss Law. This means that as the temperature increases further above the Curie point, the material's ability to be magnetised by an external field becomes progressively weaker.
5. What is the difference between the Curie temperature and the Néel temperature?
Both temperatures mark a transition to a paramagnetic state, but they apply to different types of magnetic materials.
- The Curie temperature (T_c) is the transition point for ferromagnetic materials, where aligned parallel magnetic moments become disordered.
- The Néel temperature (T_N) is the transition point for antiferromagnetic materials, where aligned anti-parallel magnetic moments become disordered.
Essentially, the Curie point signals the loss of spontaneous ferromagnetism, while the Néel point signals the loss of antiferromagnetism.
6. If the Earth's core is primarily made of iron, why isn't it a giant permanent magnet?
This is a classic application of the Curie point concept. The temperature of the Earth's outer and inner core is estimated to be between 4,000°C and 6,000°C. This is significantly higher than the Curie point of iron (770°C). Because the iron in the core is in a molten state and far above its Curie temperature, it cannot sustain a permanent, ordered magnetic state (ferromagnetism). The Earth's magnetic field is instead generated by the movement of molten iron in the outer core, a process known as the dynamo effect.
7. Is the magnetic transition at the Curie point reversible?
Yes, the transition is reversible. If a material heated above its Curie point is cooled back down, it will regain its ferromagnetic properties once it drops below the Curie temperature. However, it will not necessarily become a magnet on its own. The magnetic domains will reform, but their overall alignment will be random. To remagnetise the material, it must be cooled below its Curie point while being exposed to a strong external magnetic field, which aligns the domains as they form.
