Antiferromagnets have generated significant interest for future computing technologies due to their fast dynamics, their ability to generate and detect spin-polarized electric currents, and their robustness against external magnetic fields. Despite these bright prospects, the vanishing total magnetization in antiferromagnets makes it difficult to evaluate their internal magnetic structure compared with their ferromagnetic counterparts.
Limited understanding of the internal magnetic structure of antiferromagnetic materials and devices is a major obstacle to manipulating and efficiently utilizing variations in their magnetic state. In work that sheds light on a new set of antiferromagnetic materials, an international research team led by researchers at the National Institute of Standards and Technology (NIST), the United States Naval Research Laboratory, the Johns Hopkins University, the Institute for Solid State Physics (ISSP), and the University of Tokyo have identified a metallic antiferromagnet (Mn3Sn) that exhibits a large spontaneous magneto-optic Kerr effect (MOKE), despite a vanishing total magnetization at room temperature. A metallic antiferromagnet with a large spontaneous MOKE promises to be a vital tool for future antiferromagnetic memory devices, where the device state could be read optically and switched either optically or with a spin-polarized electric current.
In a major breakthrough for cancer research a team from Polytechnique Montréal, Université de Montréal and McGill University, Canada, have developed nanorobotic agents able to administer drugs with precision to targeted cancerous cells of tumours. Injecting medication in this way ensures the optimal targeting and avoids jeopardising organs and the surrounding tissue.
The nanorobotic agents are made of over 100 million flagellated bacteria, giving them the ability to self-propel. The agents are filled with drugs and move alone the most direct path between the injection point and the area of the body to cure. The propelling force of the agents is enough to travel and enter the tumours.
Once inside a tumour, the agents can detect oxygen-depleted areas, known as hypoxic zones, and deliver the drug to them. Hypoxic zones are resistant to most therapies, including radiotherapy.
The bacteria that make up the agents rely on two natural systems to move around. The synthesis of a chain of magnetic nanoparticles acts as a compass, allowing the bacteria to move in the direction of a magnetic field, while a sensor measuring oxygen concentration enables them to reach active tumour regions. The bacteria were exposed to a computer-controlled magnetic field, showing the researchers that it can perfectly replicate artificial nanorobots.
The researchers say that the nanorobots open the door for the synthesis of new vehicles for therapeutic, imaging and diagnostic agents, as well as having use in chemotherapy by eliminating the harmful side effects by targeting the affected area.
In a paper published today in “Science Advances,” Jing Shi, a professor of physics and astronomy at the University of California, Riverside, and colleagues at Massachusetts Institute of Technology (MIT), and Arizona State University report they have created a TI film just 25 atoms thick that adheres to an insulating magnetic film, creating a “heterostructure.” This heterostructure makes TI surfaces magnetic at room temperatures and higher, to above 400 Kelvin or more than 720 degrees Fahrenheit.
The surfaces of TI are only a few atoms thick and need little power to conduct electricity. If TI surfaces are made magnetic, current only flows along the edges of the devices, requiring even less energy. Thanks to this so-called quantum anomalous Hall effect, or QAHE, a TI device could be tiny and its batteries long lasting, Shi said.
Engineers love QAHE because it makes devices very robust, that is, hearty enough to stand up against defects or errors, so that a faulty application, for instance, doesn’t crash an entire operating system.
Researchers at the U.S. Department of Energy’s Ames Laboratory discovered that they could functionalize magnetic materials through a thoroughly unlikely method, by adding amounts of the virtually non-magnetic element scandium to a gadolinium-germanium alloy.
It was so unlikely they called it a “counterintuitive experimental finding” in their published work on the research.
“People don’t talk much about scandium when they are talking magnetism, because there has not been much reason to,” said Yaroslav Mudryk, an Associate Scientist at Ames Laboratory. “It’s rare, expensive, and displays virtually no magnetism.”
“Conventional wisdom says if you take compound A and compound B and combine them together, most commonly you get some combination of the properties of each. In the case of the addition of scandium to gadolinium, however, we observed an abrupt anomaly.”
Years of research exploring the properties of magnetocaloric materials, relating back to the discovery of the giant magnetocaloric effect in rare earth alloys in 1997 by Vitalij Pecharsky and the late Karl Gschneidner, Jr., laid the groundwork for computational theory to begin “hunting” for hidden properties in magnetic rare-earth compounds that could be discovered by introducing small amounts of other elements, altering the electronic structure of known materials.
Australian researchers and their colleagues from Russia and China have shown that it is possible to study the magnetic properties of ultrathin materials directly, via a new microscopy technique that opens the door to the discovery of more two-dimensional (2D) magnetic materials, with all sorts of potential applications.
Published in the journal Advanced Materials, the findings are significant because current techniques used to characterise normal (three-dimensional) magnets don’t work on 2D materials such as graphene due to their extremely small size – a few atom thick.
“So far there has been no way to tell exactly how strongly magnetic a 2D material was,” said Dr Jean-Philippe Tetienne from the University of Melbourne School of Physics and Centre for Quantum Computation and Communication Technology.
“That is, if you were to place the 2D material on your fridge’s door like a regular fridge magnet, how strongly it gets stuck onto it. This is the most important property of a magnet.”
To address the problem, the team, led by Professor Lloyd Hollenberg, employed a widefield nitrogen-vacancy microscope, a tool they recently developed that has the necessary sensitivity and spatial resolution to measure the strength of 2D material.
Physicists at the University of Basel have developed a minuscule instrument able to detect extremely faint magnetic fields. At the heart of the superconducting quantum interference device are two atomically thin layers of graphene, which the researchers combined with boron nitride. Instruments like this one have applications in areas such as medicine, besides being used to research new materials.
To measure very small magnetic fields, researchers often use superconducting quantum interference devices, or SQUIDs. In medicine, their uses include monitoring brain or heart activity, for example, while in the earth sciences researchers use SQUIDs to characterize the composition of rocks or detect groundwater flows. The devices also have a broad range of uses in other applied fields and basic research.
The team led by Professor Christian Schönenberger of the University of Basel’s Department of Physics and the Swiss Nanoscience Institute has now succeeded in creating one of the smallest SQUIDs ever built. The researchers described their achievement in the scientific journal Nano Letters.
Folk Names: Magnetite, Magnet, Way Stone, Magnetis (ancient Greek), Loadstone, Shadanu Sabitu (ancient Assyrian), Heraclean Stone, Piedra [man (contemporary Spanish) Energy:Receptive Planet:Venus Element:Water Associated Herbs: Sandalwood, Rose, Yarrow, Lavender Associated Star: Polaris (the North Star) Associated Stone:Coral Associated Metals: Iron, Copper, Silver, Gold Powers: Power, Healing, Attraction, Friendship, Love, Fidelity, Male Sexual Dysfunction, Will, Protection, Business, Money, Games of Chance
Magical/Ritual Lore:
Legend has it that the ancient Romans had a statue of Venus made of lodestone and an image of Mars fashioned of iron. When the two statues were placed near one another in the temple, Venus attracted Mars.
Tales (never substantiated) also sing the praises of a statue that was permanently suspended in the air through the use of lodestones.
The stone was associated with the hero Hercules in times past and so came to be a symbol of strength and invulnerability.
In contemporary folk magic, the lodestone is thought to be alive. It is placed in a small bowl of water on a Friday to allow it to “drink," then laid in full sunlight to dry. When dry, iron filings are sprinkled on it as "food.”
Though there are variations on this procedure-some keep the stone in a red bag and sprinkle water and iron filings on it once a week-it is a common belief.
Several hundred years ago it was believed that it was dangerous to carry a lodestone during a thunderstorm because it attracted lightning.
A knife rubbed with the stone was not only magnetized, but any wound inflicted with it, however small, was thought to be fatal.
The lodestone was once believed to be stripped of its magnetic as well as magical powers by the mere presence of a diamond or garlic. Giambattista della Porta, in his monumental 1558 work, Natural Magic, said he had disproved such beliefs.
Nevertheless, some still believed this was true. Fortunately, there was an easy way to restore the lodestone’s powers. It was anointed with linseed oil, placed in a goatskin bag and covered with dirt for three days.
Its use to strengthen virility and to cure male sexual dysfunction (impotency) spans the ages. In ancient Assyria it was used in a sexual rite of pure sympathetic magic. The man placed a lodestone in oil and rubbed the resulting “infusion” on his body and penis to ensure satisfactory sexual intercourse. The woman rubbed parzilli, or iron powder, on her body to enhance her attractiveness. Thus prepared, couples three thousand years ago magically (or psychologically) released their inhibitions and shared pleasure.
Comparatively recently, in 16th-century India a king ordered his cooking utensils to be fashioned of lodestone to ensure his continuing virility.
Prostitutes once used lodestones to attract customers, and thieves relied on them to hide from authority.
All this lore has sprung from the lodestone’s natural magnetic quality. It and artificially created magnets share the power of attracting iron. Five hundred years ago this was a magical, miraculous property, and many believed a spirit or demon lived within the lodestone and gave it power.
Though scientific investigation has explained magnetism to a certain extent, the lodestone continues to be used in spell and ritual.
This is especially true in Mexico, where it is sold in botanicas along with candles, incenses, religious medals, snakeskins, oils and various other occult goods. Similar stores are found in many parts of the United States where Spanish-speaking peoples live.
Mexican street vendors who deal in magical supplies also sell lodestones. A few years ago I bought one from a woman who sat on the curb in a Tijuana district unfrequented by turistas.
It is also well known in Hoodoo and other American folk magic systems. Lodestones are sometimes painted green (for use in money spells), red (love), and white (protection). Painting them is not, of course, magically important unless you deem it to be so.
Magical Uses:
The lodestone is a power stone used to strengthen spells. It is added to sachets or herbal amulets, placed on the altar, or worn to increase the magician’s ability to rouse and release energy.
In ceremonial magic of the Middle Ages the lodestone was engraved with the figure of an armored man. This stone was utilized during rituals to empower magic.
The larger the stone, the more inherent power within it. While this is true of all stones, it is especially important with the lodestone, for the greater its size, the stronger its magnetic force.
Lodestone’s basic use in magic is attraction. Because the stone is a natural magnet, it is manipulated in ritual to draw objects or energies to its user. Thus, it can be used in any type of spell.
A simple example of this: A lodestone set in a man’s belt buckle draws success in all undertakings. This is probably because of the stone’s attracting qualities as well as its placement near what some call the ‘third chakra’, located about two inches below the navel. This energy center is associated with personal power and the will. When it is stimulated by the presence of the lodestone, it expands the will and therefore ensures success.
This spell, by the way, is of Mexican origin.
The lodestone, owing to its magnetic powers, is used to draw out disease and pain from the body. True healers, who send energy into a sick person to speed the body’s natural healing powers (or, specifically, to correct imbalances or blockages in bodily energy flows), may use the lodestone as a focusing device for their energies.
The stone can be passed over or placed directly on the afflicted part of the body. This is particularly true of pain in the hands and feet.
It is also carried, often anointed first with a healing-type oil such as sandalwood. Any lodestones used in healing rituals to absorb disease should be cleansed after each use.
It is said to be effective in treating rheumatism and headaches, and in healing wounds. Placed in a black bag which was suspended on a black ribbon around the neck, it was a specific for gout a few centuries ago.
A small lodestone set in silver was thought to sharpen the sight. Set in gold, the lodestone strengthened the heart. A folk spell designed to heal the body of any illness is quite simple: Hold the lodestone in your hands, then shake it vigorously while visualizing your illness draining from you and going into the stone. Bury the stone in the earth for a week following the ritual.
Any lodestone used in healing rituals to absorb disease should be cleansed after each use or, if worn, every week or so.
The lodestone is also worn or carried to attract friendship. If you’ve just moved to a new city or have started a job among unknown people, wear or carry a lodestone to meet new friends.
The lodestone is also utilized to attract love. It is thought to be a magnet for hearts as well as for iron, especially when worn in a ring.
Place a pair of the stones within a circle of pink or red candles while visualizing yourself involved in a relationship. Feel the strong contact, the mingling of energies that comes with love. Visualize as well.
Two lodestones are also often carried in small red bags for this same purpose, sometimes mixed with love-attracting herbs such as rose, yarrow, and lavender (as well as copper, another love-inducer).
The lodestone is also worn to smooth over troubles in a relationship, especially arguing. Its basic function is to cool tempers to allow true communication.
A coral necklace with a lodestone suspended from it was once worn to facilitate easy childbirth.
In American folk magic, women wear lodestones to ensure that their wandering husbands will return home; thus, it stimulates fidelity.
Since this borders on manipulation, as does all fidelity magic, it deserves a few words here.
When you begin a loving/sexual relationship with another person, and especially when children result, you have relinquished some control over your life to your mate and family. This is part of the giving involved in strong emotional ties.
At best such fidelity magic should be used to gently remind your partner of his or her obligations. If a relationship has ended, that's that-all the spells and lodestones in the world won’t recapture the ecstasy, quiet peace and emotional fulfillment that love produces.
Psychic or magical enslavement isn’t love.
The lodestone’s ability to overcome impotency has been mentioned above, but such drastic or complex methods needn’t be used.
A man suffering from sexual dysfunction can hold the stone in his receptive hand, visualizing satisfactory, complete, joyous sexual relations.
Once this is done, he can carry the stone with him or place it beneath the mattress to release its powers. The stone and the visualization work toward rooting out the underlying cause of the sexual dysfunction.
The lodestone has also been utilized as a protective amulet, being worn, placed in the home, or carried. A large lodestone surrounded by flaming white candles emits guarding energies throughout the house. It absorbs negativity but does not return it. Because of this such stones should be cleansed in salt water every Full Moon.
Some carry two lodestones at all times-one to protect, the other to bring good luck. In ancient Spain carrying a lodestone was thought to guard against all dangers from steel, lead, fire and water.
For those lacking in will power (which is simply asserting yourself and acting in accordance with your goals), empower a lodestone through your visualization with this specific directive: “Strengthen my will.” Then carry the stone and utilize the energies it sends you. As I mentioned above, it can be worn two inches below the navel or placed there while you are prone and visualizing yourself as being confident and secure.
Because it is an attracting stone, the lodestone is used to draw money or business success. Place lodestone in a green bag with a silver coin, a bit of gold (ifyou have it) or money-attracting herbs such as patchouly, cloves or tonka. Business people may place an empowered lodestone in the cash register or cash box or burn green candles around a lodestone to bring in customers.
Finally, the lodestone is considered by some to be a potent gambling talisman. It is worn or carried for luck during betting.
[Source: Cunningham’s Encyclopedia of Crystal, Gem, & Metal Magic by Scott Cunningham]
